WorriedSis,
In my experience with addicts, it sounds like he's on Heroin, I could be wrong as each person takes on different behaviors, but this is what it's sounding like. The important thing is to let him know that you are aware that there is a drug problem going on and to not be ashamed in admitting it. The thing you and your family have to realize and this is so very hard to understand because all loved ones want to fix or control the addiction for them but you must know until he admits his addiction and says he needs/wants help there really is nothing you can do except let him know your always going to be there when he's ready for the help, if that day still hasn't come for you yet then giving him information about addiction might open his mind a little, he still won't take it serious if he's not ready. Also it's important to not enable his addiction, no money, no rides, just be there for him in a different way. It takes such a toll on the family because all we want is for them to be sober and safe and happy again, but it is such a waste of emotions and energy if they aren’t willing to admit their problem and accept help, this doesn’t mean you stop asking every time you speak or see him, that way he knows you will always be there when he is ready. I would advise you and your family to educate yourselves on drug addiction, it helps to understand addicts a little more, remember this is an illness and they don't purposely do this to hurt other's, they are sick and need help. Rehab and therapy will be the second step after he admits his problems.