What is the cause of black stool and blood in stool with constant stomach pain 35 year old male

Ulcers. Bright red blood in the stool is from hemorrhoids. Black stool is digested blood from stomach ulcers. These can be treated with Prilosec and suppositories. Get tested for h.Pylori. You're not too far gone to recover, but this is going to take some work. Hopefully, your fp can discover the cause of your bleeding (alcohol?), diagnose and treat properly, so that you can get to feeling better soon!