What Causes Painful Pressure In The Stomach During Pregnancy?

I am 29 years old. I started noticing this issue when I was pregnant. I remember eating something and a couple of minutes later I felt this painful pressure come up from the bottom of my stomach to the top of my stomach and kind of stay there,I thought I was having a heart attack. I got on all fours and began belching until eventually the pain subsided. At the time when I asked my doctor about it he told me to take tums and I should be fine, that this was brought on by me being pregnant. After I had my child I would still continue to get this feeling from time to time. Same symptoms. Now it has gotten to the pint where it sits there and continues to be painful to the point where I feel led to throw up just to feel better. Never once doing this has made the symptoms go away. The pain stays longer now and the next day I don t eat at all. Any idea of what this might be. It happens after I eat no matter what I eat. I use to think it was trapped gas but I am afraid that it could be more worse.