Why?!?!

You guys my baby was a dream boat - he was sleeping through the night consistently since he was 6 weeks old he’s now 15 weeks. We would nurse at 9:00 pop him in his bath, get him ready for bed and he would nurse himself to sleep. I made sure he was burped and then put him to bed at 10:30. He would sleep until 6:30 only occasionally getting up at 4:30. And then either way he would sleep until 9:30 or 10. The last 2 weeks have been hell. He is restless and wakes nearly every hour. Usually because he is farting or needs to burp. I am beyond exhausted. He will sleep peacefully if I hold him but as soon as I set him down he begins to squirm. Last night he fully woke and wanted to eat at 1:00 and 4:00 and again at 6:30. On top of that he is also wriggling around the bed and fussing out every hour. We’ve given gas drops, kid e col, gripe water. I spend most of an hour after each feed burping him, moving positions to get him to burp better. Gah!!! What do I do?!?