my dog has blackheads on his elbows...

i got his elbows checkex 3 times... same vet... all said it was just hair loss from him laying down... well i looked at his elbow today gave a small pinch cause i saw a zit and he seemed irritated by it... well when i squeezed it all the "hair" from the "hair loss" came oozing out with a bunch of puss from several "hairs" that were in the pinched skin. looked it up online. yes his elbows r covered in blackheads and my dumbass vet has been telling us its hair loss... he doesnt seem uncomfortable with the grossness coming out but he seems annoyed with it being left like that... (he wont stop trying to lick his legs... ive been stopping him each time i catch him doing so to check the area. never found anything till now...) any one else have this problem?