I know this is a post from a long time ago, but it probably was pain pills... Most heroin people get and smoke smells slightly bitter and vinegary, nothing compares to the sweet smell of smoking oxy or other pills, and they are normally smoked off of foil in the way you described. A good way to tell what kind of pill he is smoking is to look up the ID number/lettering on the front of the pill if you can get him to show you one before it is broken up or crushed to smoke. And doing pills makes you irritable as all hell.