Been having loose stools, getting worse, smell like sulfur, feel weak and tired all the time an in the past couple months have lost over 20 pounds....

Gastroenterologist. You need to be seen ASAP by a GI doctor. It sounds as if whatever is wrong with your GI tract has made you anemic and is now a systemic illness, You will probably require colonoscopy and this should be done soon. Best wishes. Please make appt now.