It is very difficult for me to give you a diagnosis based on the information you have given. You haven’t specified the actual tests you have undergone but you do say that they were numerous. Taking that at face value that indicates to me that your bowel is normal. Perhaps your diet is at fault. You may not be eating a sufficiently broadly based diet and in particular you may not be getting adequate amounts of roughage or fibre in your diet. Perhaps your physical symptoms are of psychological origin. I make that statement very gently because many people become offended if a doctor suggests a psychological basis for symptoms. I am not saying, “that this is all in your head”, to use the common colloquial expression. Psychological conflict can create physical symptoms and those real physical symptoms can be just as severe and intense as physical disease. Alternatively perhaps there is a cyclical element to your symptoms that may indicate a hormonal basis to them. I would suggest that you return to your GP and discuss this problem again. In the meantime you might reflect on my suggestion about a possible psychological origin for your complaint.