Hi, I am 22 years old and recently I've been having some weird problems with my stomach. I have been having constant diarrhea, my stomach has been hurting alot before or after I eat pretty much most of the time. In addition, when I eat, all of a sudden I vomit in between the meal and then I am not able to eat any more because nothing will go down, (this is not voluntary and I am not bulimic), I have also been experiencing some lower back pains and chest pains. I realized I gained about 15 pounds in two months (I've been trying to gain weight for a while too), could this problems be as a result of my weight gain or what do this be?