What Causes Abdominal Discomfort And Bloating?

Hi I am having some stomach issues that I need help with. For the past few weeks my stomach has been totally bloated. I have that feeling of when you ve eaten too much and feel like you re going to explode, all the time even when I haven t eaten. I can t even suck in my stomach. I have no idea what s going on, it s so uncomfortable and makes me feel terrible. The only two factors that I can think of that might have to do with it are: 1) I just restarted up on birth control last month 2) I have just started eating meat again after being a vegetarian for 6 years. I have no idea if these have had an effect but it s worth mentioning. Please help.