Dry/scab/kinda loss of hair/ on horses back lower legs?

i just have been seeing these spots on my horses back lower legs on the "cannon" .one spot was big kinda looked like the chestnuts but it had hair on it and i putted the scab off it didn't hurt him and it liked dry under it and there was little hairs there but the spots are not all big some are little spots too and they all do the same thing, my horse is very well kept and is ever in the rain out in pasture during day and in stall at night, do you have a idea of what this could be? i put some Wound Care stuff on it for dry skin and cuts for the time being. but thanks for the help