I'm sorry you're going through this. It sounds miserable!
My initial reaction is that you should make an appointment to see a medical professional. Diarrhea (by which I mean mostly watery stool with little to no solid waste in it) lasting longer than a week is not normal for an adult. Usually, if diarrhea is caused by food poisoning, it resolves within a few days. The pain you describe in conjunction with the diarrhea also is concerning.
While I'm not suggesting you have any type of life-threatening condition, I would suggest you make an appointment with your primary care provider as soon as possible.
Meanwhile, it's crucial for you to drink plenty of fluids. Because your diarrhea has been going on for so long, you might also want to sip a sports drink like Gatorade. Dehydration might explain why you feel so weak.
I wish you all the best in finding out what's causing this problem!
Important: The opinions expressed in WebMD User-generated content areas like communities, reviews, ratings, blogs, or WebMD Answers are solely those of the User, who may or may not have medical or scientific training. These opinions do not represent the opinions of WebMD. User-generated content areas are not reviewed by a WebMD physician or any member of the WebMD editorial staff for accuracy, balance, objectivity, or any other reason except for compliance with our Terms and Conditions. Some of these opinions may contain information about treatments or uses of drug products that have not been approved by the U.S. Food and Drug Administration. WebMD does not endorse any specific product, service, or treatment. Do not consider WebMD User-generated content as medical advice. Never delay or disregard seeking professional medical advice from your doctor or other qualified healthcare provider because of something you have read on WebMD. You should always speak with your doctor before you start, stop, or change any prescribed part of your care plan or treatment. WebMD understands that reading individual, real-life experiences can be a helpful resource, but it is never a substitute for professional medical advice, diagnosis, or treatment from a qualified health care provider. If you think you may have a medical emergency, call your doctor or dial 911 immediately.