What is going on with this mole and should I be worried? (photo)

It has doubled in size in short time(on my back, not 100% sure when). Isnt painful unless pushed hard, numb feeling now after i messed with it a little. Son with delays noticed and said get out of their(noticeably bigger and changed). I have had sun poisoning a few times but dont tan or go out without spf. I have tons of big to small moles all over my body. I dont get them checked even though i should.