I had that same exact problem starting at 31 weeks and ended around 34 weeks on and off. It always happened at night wen I tried to sleep. Doctor said it was most likely just a big she said eat lots of soup and drink water and gaterade and it went away eventually. But if you starting throwing up 3 times a day for over 3 days straight u should go to doctor.
My sister suggested it could be my gallbladder
I would go to hospital to run tests and get a second opinion just to be sure
I've asked my doctor about it, they don't know what it is and haven't had any worrys about it..
Umm I would call your doctor that doesn't sound very good and u hate for somthing to go wrong that far along In you pregnancy! I hope u and you baby are Ganna be ok!