What is best way to stop diarrhea. Everyday for years.

Full GI exam. A complete GI series exam may be the answer. Testing for food allergies is another idea. Also, ask your provider for a proper diet and perhaps a referral to a nutritionist. If you think or they find no physical cause - a specialist in dietary issues psychotherapist might be an additional resource. Best!
Get evaluated. Chronic diarrhea for years implies an underlying medical condition. Best way to stop it is to find out what is causing it!
Supplements. My mom had great results with probiotic, enymes and aloe. Ask your doc for medical reasons.