I have been having a bad pain in my stomache since yesterday morning when upon waking with a bad back ache and headache I took two advil liguid gels on an empty stomache which I normally do not do and in about 10 minutes I was having intense stomache pains, and I drank a glass of milk which helped but the pain has never went completely away. It is still hurting and I have tried everything to make it stop including pepto bismol tablets. I just had a bowel movement that was black and rubbery. I investigated and inside was normal color but the outside was a rubbery black consistency. Is the color from the pepto? What caused the rubbery casing around my stoll?