i have a quarter size white lump on my back surrounded by a large red and purple area that seems to be betting bigger everyday. it is warm and very tender and sensitive. I went to my general doctor and he prescribed me antibiotics but it hasn t seem to affect it much. he didn t know what caused it but thinks it might be a bite but said there was nothing else he could do. Its so painful I can t sleep , i can t move my right arm very much since it s on my right shoulder blade and I just need relief!