Jet black stool is not COOL..........Im a poet and didnt know, hehe........
Seriously, go to the doc, and I would go to emergency as Jet black stool is a very strong indication that you have some internal bleeding going on, GI bleed?????? Not good my man. Any other symptoms? emisis(vomiting that is), nausea, stomach pain, fatigue, febrile(fever)? If you have any of these symptoms, then go get checked out by a doc, and like I said, I would go straght to emergency. Your from UK? Medical visits are free are they not? what do you have to lose to gain some peace of mind????????