Are both sentences OK?
You'd better go to a hospital and get that checked.
You'd better go to a hospital and get that looked at.

Question

Answer

They both sound correct and natural to me.

Answer

The first sentence sounds better and would be more commonly used. The second one is also correct and would be used for an illness which is more visibly prominent.

Answer

I suppose that the first sentence is correct. Because when you "Check" something it means that you look at it carefully in order to make sure that it is correct, safe or working properly.

Evden çıkmadan dil öğrenme fırsatını kaçırmayın. Deneyimli dil eğitmenlerimizden oluşan seçkimize göz atın ve ilk dersinize şimdi kaydolun!