A Couple Days Ago I Notice A Pain On My

a couple days ago I notice a pain on my back. my friend said it was a spider bite. I have never had a spider bite to my knowledge. but it started to get bigger and is now a big raised very hard red bump. the size of a quarter. on the second day another appeared on my lower back and the day after another all are getting better is warm to the touch and hard. it hurts when I lean back on them but otherwise it is very mild stinging feeling. the middle has a dot,