Hi there ~
I understand your concerns. Difficulty in moving elbow with having a lump in the arm after injecting yourself in the area with meth
seems to me like a bad vein that ruptured with hemorrhage as well as probably infection, depending on the cleanliness of the needle. You need to visit with a doctor as soon as possible. It is for your own safety. I would advise you not apply anything on the wound till he sees the doctor. Keep the area dry and clean and visit with and consult a doctor as soon as possible.
I hope this helps. Take care and have a lovely day!