Every time i swallow it feels weird, i've been feeling nauseous bt i dnt throw up i just burp and pass gas?

i had sex last web, then i had a period the day after. Four days later my period stopped and now i've been feeling like this. My stomach hurts after i eat, and i have bad stomach pains sometimes when i wake up. My stomach will fill full after barely eating anything. I have to lay on the heating pad to make my stomach stop hurting or sometimes go to slp and then my stomach will still hurt. I don't think im pregnant, i have gallbladder and indigestion problems. What do you think is going on???