I am a healthy 58 year old woman. I have had a hard little, pea sized thing on my back for about 2months now. In the last 3 days it has started to grow larger. It has turned red and the skin is very painful to the touch now. It doesn't have a head on it to pop it. It feels like it is very deep in the tissue. I am getting very uncomfortable now when I try and sit back on it. I have a dermatologist apt next Tuesday but I'm really worried it will be huge by then or will bust open. What does this sound like? A boil, possibly? I have never had one before. Thank you for any ideas that you may have. It is on my left side of my inner back next to my shoulder blade. I can't reach it with my hand.