Major stomach discomfort - I have no idea what it is?

During the day I experience a burning sensation in my stomach every now and then - towards the evening I feel VERY uncomfortable. I don't know how to describe it - it's like a mixture of nausea and bloatedness and flatulence. I just had dinner and I had to stop halfway because I had difficulty swallowing. It felt like the food was in my chest or something - the feeling ped and now my stomach just feels heavy and uncomfortable. It feels like something is going to come up, or like something is trapped in my stomach. My stomach hurts sometimes as well. I feel ill almost all the time and it makes it difficult to fall asleep. Help?