Hi. Thanks for your query. Noted the history and understood your concerns. You should not ride over such issues unless properly diagnosed and treated. Sharp shooting pain in tummy that shoots down to butt and pain on sitting indicate that you may have painful coccyx along with proctitis that can cause such pains. I would advise you the following: Get clinical examination, per-rectal digital examination and sigmoidoscopy to know what exact the problem is. Get an analgesic to counter the pain and the further treatment will be as per the diagnosis made. Have Sitz bath in a tub with warm water. May need an opinion of a Gastro Surgeon and further investigations and an active treatment as needed.