Learn Turkish: Hastalık daha beter olacaktı, iyi ki doktora gittim. - The illness was going to be worse, fortunately I went to the doctor.

İyi ki translates to "fortunately" or "it's a good thing that." It expresses relief. Unlike some Turkish structures that require special verb forms, iyi ki is simply followed by a regular, conjugated finite verb. Here, it just uses the standard past tense gittim (I went).

What tense is olacaktı and why is it used here?

Olacaktı is the "future in the past" tense. It is made by combining the future suffix -acak with the past tense suffix -tı. It means "was going to be." It is used here to show an event that was expected to happen (the illness getting worse) but was prevented because you took action.

Could I say daha kötü instead of daha beter?

Yes, daha kötü also means "worse" and is completely fine here. However, beter carries a slightly stronger, more dramatic tone, similar to "awful" or "terrible." Using daha beter emphasizes your relief that you stopped the illness from becoming severe.

Why is iyi ki written as two separate words?