On and Off Pain

Hello,I am new to this site and I am not exactly sure what I am doing.. I am 19 years old and have been experiencing abdominal and other forms of pain for several years now. My pain seems to come in waves. For example, there will be a week where I can eat anything and however much I want without any form of pain. But other times such as the past month and especially for the past week I have been experiencing extreme amounts of pain in my lower stomach. When my pain does come about it is usually the same as always. I need to use the bathroom very urgently and would describe my pain to be something comparable to knives shooting through my stomach. It starts off very hard, as if everything was clogged, and then turns to diarrhea. After one of these episodes I feel completely drained of all my energy and can't do much more than sit or lie down for a half hour or so. I have seen different doctors and tried different medicines to try and help regulate my system. I try and reduce my stress and eat healthy small meals throughout the day. This helps to a certain degree but nothing has seemed to last for very long. Everything feels very irregular. Does anyone know of something that I can do or try?