I went through the same thing with ds at this age. Frustrating and exhausting

My best advice would be starting the day sleeps again, and trying an earlier bed time. Sleep breeds sleep and over tiredness will make the problem worse.

Have you tried the book The No Cry Sleep Solution? It's fantastic and her methods really do work as long as your consistent (which is very difficult when you're so tired, I know). It takes a week or two, but well worth it- no crying required

Hang in there hun, I know how much it sux but it can't last forever