Sleep schedule!

My 8 month old is getting over the flu, he had a super high fever and wasn’t able to sleep at all. Until I gave him a really good medicine and he slept all day, and nearly all night. Well now his sleep schedule is horrible, he sleeps til 5 pm and yes he will sleep through most of the night like 8-12 or 1 am, but after that he wakes up for an hour or so before I settle him again, and we repeat that then at 4 am he’s up til 6-7 am. Then the cycle repeats. What do I do? He’s still sort of sick even tho fever is gone he now has cough. How do I fix this?