Dünden beri hapşırıp duruyorum, bu yüzden bugün evde kalıyorum.

Because beri normally follows a word in the ablative case when it means since.

• dün = yesterday
• dünden = from yesterday / since yesterday
• beri = since, for

So dünden beri means since yesterday.

This pattern is very common:

• sabahtan beri = since morning
• iki günden beri = for two days
• çocukluğumdan beri = since my childhood

So the -den ending is not optional here in standard Turkish.

Beri is a postposition that usually means since or for (a period continuing until now).

In this sentence, dünden beri tells you that the sneezing started yesterday and has continued up to now.

It is different from a simple past-time expression like:

• dün = yesterday

If you only say Dün hapşırdım, that means I sneezed yesterday.
But Dünden beri hapşırıyorum means I have been sneezing since yesterday.

Hapşırıyorum simply means I am sneezing.

But hapşırıp duruyorum adds the idea of repeatedly or continuously doing it, often with a sense like I keep sneezing.

So:

• hapşırıyorum = I’m sneezing
• hapşırıp duruyorum = I keep sneezing / I’ve been sneezing over and over

This structure is very common in Turkish when the speaker wants to emphasize that an action keeps happening.

The -ıp / -ip / -up / -üp form is a kind of converb or linking verb form. It connects one verb to another.

Here:

• hapşır- = sneeze
• hapşırıp duruyorum = sneezing and continuing / keep sneezing

The exact form changes by vowel harmony:

• alıp
• gelip
• oturup
• görüp

In this sentence, hapşırıp links the main action hapşırmak to the auxiliary-like verb durmak.

Not literally. In hapşırıp duruyorum, durmak is acting more like an auxiliary verb.

By itself, durmak can mean things like:

• to stand
• to stay still
• to stop

But after another verb in the -ıp form, it often gives the meaning to keep doing something.

So here it does not mean I am standing.
It means something more like:

• I keep sneezing
• I’m sneezing nonstop
• I’ve been sneezing repeatedly

Because this is the present continuous form of durmak:

• stem: dur-
• present continuous suffix: -uyor
• 1st person singular: -um

So:

• dur-uyor-um → duruyorum

The y is part of the progressive suffix here. You will see the same pattern in many verbs:

• geliyorum
• bakıyorum
• oturuyorum
• duruyorum

Because both actions are relevant right now.

• hapşırıp duruyorum = I keep sneezing / I’ve been sneezing
• evde kalıyorum = I’m staying home

Turkish often uses the present continuous -yor where English might use either:

• am doing
• have been doing
• sometimes even a near-future sense like I’m staying home today

So the tense fits both parts naturally:

1. an ongoing condition since yesterday
2. today’s current decision/action

Bu yüzden means because of this, for this reason, or simply so.

It connects the first part of the sentence to the result:

• Dünden beri hapşırıp duruyorum = I’ve been sneezing since yesterday
• bu yüzden bugün evde kalıyorum = so / for that reason I’m staying home today

Other similar expressions are:

• bu nedenle = for this reason, therefore
• onun için = that’s why / for that reason

Bu yüzden is very natural and common.

Because evde kalıyorum emphasizes the action/decision of staying at home, not just the fact of being at home.

Compare:

• Evdeyim. = I am at home.
• Evde kalıyorum. = I am staying at home.

In this sentence, the speaker is explaining a choice or plan caused by the sneezing, so kalıyorum is better.

It suggests:

• I’m remaining at home
• I’m not going out
• I’m staying home because of the situation

Evde is ev + -de, the locative case.

• ev = house, home
• evde = at home / in the house

The locative suffix -de / -da / -te / -ta means in, at, on depending on context.

Examples:

• okulda = at school
• işte = at work
• masada = on the table
• evde = at home

So evde kalıyorum literally means I am staying at home.

Yes, but that is completely normal in Turkish.

The verb ending already tells you the subject:

• duruyorum = I am continuing / I keep...
• kalıyorum = I am staying

Because the -um ending marks first person singular, Turkish usually does not need a separate pronoun like ben unless the speaker wants emphasis.

So:

• Ben evde kalıyorum = I am staying home
• Evde kalıyorum = I am staying home

Both are correct, but the second is more neutral and natural in many contexts.

Yes. Turkish word order is flexible, although some orders sound more natural than others.

The given sentence is very natural:

• Dünden beri hapşırıp duruyorum, bu yüzden bugün evde kalıyorum.

But you could also say:

• Bugün bu yüzden evde kalıyorum.
• Bu yüzden evde kalıyorum bugün.
• Dünden beri hapşırıp durduğum için bugün evde kalıyorum.

The basic meaning stays similar, but the emphasis changes.

In the original sentence:

• dünden beri is highlighted first as the background
• bu yüzden clearly introduces the result
• bugün evde kalıyorum gives the conclusion

Yes, absolutely. That would be correct and natural.

• Dünden beri hapşırıyorum. = I’ve been sneezing since yesterday.
• Dünden beri hapşırıp duruyorum. = I keep sneezing since yesterday / I’ve been sneezing over and over since yesterday.

The second version is more expressive and emphasizes repetition or persistence.
The first is simpler and more neutral.

Yes. It often carries a slight feeling that the action is:

• repetitive
• ongoing
• annoying
• hard to stop

So it sounds very natural for things like:

• öksürüp duruyorum = I keep coughing
• sorup duruyor = he/she keeps asking
• konuşup duruyorlar = they keep talking

In this sentence, it helps convey that the sneezing is not just one sneeze, but a continuing problem serious enough to make the speaker stay home.