Pain In Abdomen, Back, Headache, Nausea, Diarrhea, Feeling Of Vomiting, Shivers. Black Stools After Bita Bismol Intake. Advice

I need help!! Well my stomach started hurting since last Wednesday it's been 5 days and my stomach hasn't stop hurting not exactly my stomach but its my abdomen in both sides and all around my back. At first i though it was just cramps because i got my period that day and my legs hurt pretty bad that day too and my legs hurt like that when im on my period so i thought it was normal but i been like this for five days( my legs dont hurt anymore though) but when I poop it comes out literally like water all destroy and i have nussias and my head hurts at night. I wasn't able to eat anything for two days I just wanted to trow up everything but I couldn't, I wouldn't even get hungry I started to eat but I can barely eat anything I just want to throw up everything. I feel cold all the time and I get the shivers all day mostly at night and today my mom bought me petobismol and I took some but my stomach still hurt and when I went to the bathroom and when I try to wipe i saw blood but im not sure if it is because of my period or if i just bleed from my butt and today when I went to the restroom my poop came all black but I read petobismol makes your poop black so idk if my insides is bleeding or it's just the bitabismol? Can you help? Can you tell me what's wrong with me?