I've had this since I was young, but I thought it was pretty much normal, so I don't really know for sure if I've always had it, or when it started as a child. I'm 31 now.
This occurs after eating food, or even drinking. I need to take the time to really see if it's specific to some foods, or just food/drinks in general.
After eating, (not always), I can start to produce too much saliva, and it becomes very thick (i.e. if I go to the bathroom and spit it out, rather than swallowing it, it won't separate, unless I pull it apart with my fingers). I tend to end up swallowing it, more and more, and then in the worst cases (not very common) get to the point where I'm extremely nauseated and feel like vomiting. Usually I just feel bad/nauseated and have to sit/relax or else it'll get much worse.
I do not get flatulence.
I rarely vomit food out, but sometimes will make a very loud "vomiting sound" and have nothing come out, or just a bunch of saliva.
I've noticed that if I lie down on my right side, I feel a bit better while I'm lying down. However, if I turn over and lie on my left side, I immediately start to feel pressure in my stomach/intestinal area and start to feel the need to burp.
I've noticed milk products (milk in cereal, cheese on pizza, etc) and soda/pop tend to be very prone to ruining my day.