In a 501c3 do we have to have the medical form that we have filled out by our campers stamped by the Doctor with his license number on it?

This is more a question of good governance than it is a 501c(3) question. My advice is there should be a review by the doctor or other medical professoinal of each form - so that management is assured that forms have been received from all parents and that the doctor has been notified of all pertinent information (such as meds that some campers may have to take). I would bet that the American Camping Associaton has some guidelines on this - have you checked with them?