16 month old not sleeping

My ds gets one nap during the day from 1 to whenever he was up. He normally sleeps an hour and a half to two hours. His bed time is at 730 or eight depending on how long he sleeps. For the past month or so he has been waking up every 30-45 minstrel screaming. Idk what's going on but every since right before he got thebflu he's been doing this. He's never done this before.... Any advice? Suggestions on what to do or what could be causing this???

I wouldn't let him nap so late if he goes to bed at 7:30..