Fallen, I can't even begin to imagine what inner torments you are facing; my heart goes out to you.
I hope and pray that you did not go along with your sister's wishes last night. There's no such thing as a "safe" drug, and as you struggle with your ed, you certainly don't need the added complications of possibly falling into habitual drug use again. Please think about what it would do to your body, as well as your mind, sweetie. You need to be able to draw on all possible inner resources at this time.
Forgive me for being so blunt, but I think that your sister is trying to get you using again, despite all this talk about birthday presents, etc., in order to validate her own drug use. Don't give in to her!!!
You're dealing with a lot right now, including that great void left in your heart after your brother's death, but do you think that you have enough physical and mental strength to perhaps try to help your sister get off drugs? I guess what I'm asking is if you thought you could try to be there for her, as your brother was for you? I am in no way trying to lay a guilt trip on you, because I know that you barely have enough inner reserves of strength to deal with your own problems, but it was just a thought... maybe if you could try to help her, you would begin to feel a sense of purpose that has been lacking in your life, and that could help you with your own problems.
I obviously don't know anything about your family situation, except for your ed and prior drug use, your brother's death (for which I am deeply sorry; I'm sure that the pain is excruciating), and your sister's drug use. I think that your family might benefit from some counseling as a group, if there's any way to pursue that. I assume that your relationship with your parents is less than perfect, if you feel that you have "no one to turn to". It's so sad to me that you feel that way... it's of little comfort, I know, but you do have your many friends here and, as you just discovered, your support group facilitator.
Speaking of her, you said that you didn't know how you were going to get through until Wednesday, with this situation with your sister going on. Is there any way that you can call your facilitator if you ever have a problem that can't wait until the next group meeting?
Another thought I had was for you to undergo grief counseling, separate from your ed counseling. Many churches and hospitals offer free "bereavement" classes or weekly support group meetings (usually for eight weeks or so) for those who are grieving the loss of a loved one. Such classes or meetings are offered on a continuing basis throughout the year.
Your weird arm and hand symptoms sound a lot to me like dystonia, which is a neurological disorder affecting the nerves that control certain muscle groups that often go into spasm while attempting to perform a specific task. It sounds really dire, but it's not (at least based on your particular set of symptoms). Often, physical therapy will help relieve the symptoms. The best doctor to see would be a "movement disorders" specialist, but if you don't have access to someone with that expertise, then a "regular" neurologist should be able to diagnose the problem and recommend treatment options.
Good luck with everything, honey.
Hugs,
Pat
I wish I could help more,