I Am Healthy 65 Year Old Woman. For 10 Months

I am healthy 65 year old woman. For 10 months now I have bumps mainly on my back and arms (1/4 to 1/2 inch and perfectly round that itch severely. Of course I scratch them, they bleed heavily, scab up in 8 hours and repeat. Some go away (with scarring) but others crop up elsewhere. Dermatologist is at a loss. Last appointment he said he would have to try "something out of the box", doxycycline hyclate - not cheap. We've tried everything else he could think of.