Excessive burping?

First of all, I'm a 23 year old female, weighing around 126 pounds, and I'm 5'7. So, I would say I've had this issue on and off for the past year or so. I get these weird little burps that seem to be located in my throat. They don't seem to be very airy and they're not audible either, but they're constant. It's the worst at night, I'm constantly burping until I fall asleep. Sometimes, I get this gross full feeling all day where I wake up feeling like I've never digested my food from the day before and I get a little nauseas during the day. It doesn't seem to be related to my diet. about a month ago, I switched over to being a vegetarian and it went away for a few weeks, but now it's back. I sometimes wake up at around 5 am and I have to sit up, because my stomach feels full of gas. It's all burping though. I should also mention that I have hypothyroidism, but I take synthroid for it. Does anyone know what this might be? It's becoming extremely annoying. Any advice on how to stop it naturally or should I be seeing a doctor at this point?