This could be SO many things. You'll have to do some research to narrow it down. If you don't have insurance and you can afford to buy some, now might be the time.
Here are a couple of things that I've found helpful.
Research! Read old posts in this forum. There is a fantastic research resource that I've found very helpful called "The First Principles of Gastroenterology": http://gastroresource.com/GITextbook/en/Default.htm. This article has a chart with possible causes of abdominal pain: http://www.emedicine.com/med/topic2740.htm.
Log! Keep a journal. It helps identify patterns in your symptoms, foods, medications, temperature and pain level. You're welcome to read mine but I write a lot (can you tell?). :) http://www.medhelp.org/user_journals/show/12546?personal_page_id=8912
Reach Out! You are not alone! Try to stay positive.
When you do find answers,please post to let everyone know what you found and how you got rid of your symptoms. It gives people on this site hope to hear success stories.
All the best,