how much blood? like 10 tissues worth of blood or like 2? if its just a couple they probs shooting up, if its a lot theyre blowing shit.
personally ive done my fair share of both roxies (30 mg roxicodone, an opiate) and coke, up to an 8 ball a night a few nights a week, and ive never gotten nosebleeds from either. sometimes the next day ill blow my nose and some dried blood comes out but thats it. that being said ive seen a few girls who like the booger sugar, get nosebleeds while railin lines.
id say straight up ask him if he knows anyone who can get both drugs, if he is instantly like ya i cna get you some yay, hes probs doin yay. or just ask him what drugs hes doing and try to figure out by his body language, as im sure he will deny doing drugs.