I had diahrra for 4 days and was very thirsty all the time then i started to spot brown substance. also i was sick to my stomach but i have already been off my period for 7 days now?

Not sure: No sure how these symptoms correlate without a good history and physical exam..I would recommend that you make an appointment with your family doc for an evaluation.

See doctor: Diarrhea can cause water and electrolytes lost and it can cause thirsty. Another thing can cause thirsty is diabetes. You better see your doctor get a check up if symptoms persist and i also recommend increase fluid intake now. You can try otc pedialyte which contain electrolyte supplement to prevent dehydration getting worse.