kinou ha nagai kaigi no ato de katakori ga hidoku narimasita.

In this sentence, 昨日は sets the time topic: as for yesterday or yesterday, ....

Japanese often uses は after a time expression when that time is being treated as the topic or frame for the sentence.

• 昨日は = yesterday, as for that time
• It gives the listener a time context for what follows.

You could also sometimes see just 昨日 without は, but 昨日は feels a little more like the speaker is setting up the situation: Yesterday, ...

長い literally means long, and it can describe both physical length and duration.

So:

• 長い会議 = a long meeting

Here, it refers to the meeting lasting a long time, not being physically long in size.

This is very natural Japanese. Adjectives go directly before the noun they modify:

• 長い = long
• 会議 = meeting
• 長い会議 = long meeting

のあとで means after.

It is built like this:

• 会議 = meeting
• の = links the noun to what follows
• あと = after / later / the time after
• で = in this expression, part of the set phrase

So:

• 会議のあとで = after the meeting
• 長い会議のあとで = after the long meeting

This is a very common pattern:

• Noun + のあとで = after N

Examples:

• 授業のあとで = after class
• 仕事のあとで = after work

In あとで, the で is part of a common time expression meaning after or later.

In beginner study, it is usually best to learn あとで as a chunk:

• 〜のあとで = after 〜

There are related forms, such as:

• 会議のあと = after the meeting
• 会議のあとで = after the meeting
• 会議のあとに = after the meeting

These are similar, though nuances can vary a little by context. In this sentence, 長い会議のあとで is completely natural.

肩こり means stiff shoulders or shoulder stiffness.

It is a very common word in Japanese, and it is used more often in everyday conversation than a direct English phrase like shoulder stiffness might be.

So:

• 肩 = shoulder
• こり = stiffness / tension

Together:

• 肩こり = shoulder stiffness, especially from tension, posture, desk work, stress, etc.

In this sentence, it refers to the speaker’s shoulder stiffness getting worse.

Here, が marks 肩こり as the thing that changed.

The sentence is about what became severe:

• 肩こりがひどくなりました
• My shoulder stiffness became severe / got worse

With verbs like なる (to become), the thing undergoing the change is often marked with が.

So:

• 肩こりが = shoulder stiffness is the thing being described
• ひどくなりました = became severe / got worse

If you used 肩こりは, it would sound more like you were making shoulder stiffness the topic, possibly contrasting it with something else.

Because ひどい is an i-adjective, and before なる it changes into its adverbial form.

Pattern:

• い-adjective → く + なる

So:

• ひどい = severe / awful / bad
• ひどくなる = to become severe / to get worse

Other examples:

• 寒い → 寒くなる = become cold
• 強い → 強くなる = become strong
• 痛い → 痛くなる = become painful

So 肩こりがひどくなりました literally means:

• shoulder stiffness became severe

Natural English:

• My shoulder stiffness got worse.

なりました is the polite past form of なる, which means to become.

So:

• ひどくなる = to become severe / to get worse
• ひどくなりました = became severe / got worse

Because it is in the past tense, the sentence describes a change that already happened.

Also, it is polite because of ました.

So the sentence is not just describing a state; it is describing a change:

• not simply my shoulders were stiff
• but my shoulder stiffness became worse

Yes, in English we would probably say I or my, but in Japanese those are often omitted when they are obvious from context.

This sentence does not explicitly say:

• I
• my shoulders
• I had shoulder stiffness

Instead, Japanese naturally says:

• 肩こりがひどくなりました
• The shoulder stiffness got worse

From context, the listener understands that it is the speaker’s shoulder stiffness.

This kind of omission is extremely common in Japanese.

A useful breakdown is:

• 昨日は = yesterday / as for yesterday
• 長い会議のあとで = after the long meeting
• 肩こりが = my shoulder stiffness
• ひどくなりました = got worse / became severe

So the overall structure is:

[Time topic] + [after-event phrase] + [thing that changed] + [became X]

That is a very normal Japanese sentence pattern.

Yes, ひどい often means terrible, awful, or severe, but translation depends on context.

With symptoms or conditions, ひどい often means:

• bad
• serious
• severe

So:

• 肩こりがひどい = my shoulder stiffness is bad / severe
• 肩こりがひどくなった = my shoulder stiffness became bad / got worse

In natural English, got worse is often the best translation, even though the Japanese literally says something like became severe.

Yes. Japanese does not have articles like a and the, so either may be possible depending on context.

• 長い会議のあとで could mean:
  • after a long meeting
  • after the long meeting

If the meeting has already been mentioned or is understood, English might prefer the long meeting.
If it is just being introduced, English might prefer a long meeting.

Japanese leaves that up to context.

Yes. A casual version would be:

昨日、長い会議のあとで肩こりがひどくなった。

Main differences:

• は may be dropped depending on style
• なりました becomes なった in casual speech

So:

• ひどくなりました = polite
• ひどくなった = casual

Both are correct; the original sentence is simply more polite.