What Causes Swelling And Numbness On The Face Along With Dizziness?

Hello. My sister won t go into the doctor because the issue is related to drug use and she doesn t want law enforcement involved. But I am very very concerned. She relapsed and shot meth up in her neck. She says it swelled up immediately but did not bruise and the left side of her neck, face, and ear, went numb. It got better the next two days but today it began to make those areas numb again and though the swelling has gone down, now there s a small lump on the side of her neck that is painful upon touching. Every time she stands up she has to brace herself for about a minute because she gets extremely dizzy. Please help me with any ideas on what this could be so that I can help her understand that she needs to be seen. She said she just missed the vein and she will be fine, if it was gonna kill her it would have by now. Though I may be wrong and if she did just miss and it is a healing process I will feel much better I just wanted to get any advice I could. Thanks