Ruptured Cyst on Dog

My 8 y/o M golden retriever has had a marble-sized cyst under the skin on his chest for about a year (maybe longer). The vet told us nothing had to be done unless it started bothering him.

Over the last month or two it's started weeping occasionally, but I've been able to just clean it up at home. About five days ago, I noticed a large clump of blood and pus dried in the fur on top of the cyst. I cleaned it and shaved down the fur, cleaning the small wound with saline spray and applying bacitracin.

It scabbed over and appeared to be healing, but last night I had to wipe away quite a bit of thick, white pus and what appeared to be part of the cyst's sac. Now it's open again and there's still a bit of pus inside, but of course I don't want to try to drain the rest myself.

He has a vet checkup in a week and a half and I'm wondering if I should move it up or continue cleaning and monitoring it at home. I'll add that it's in a spot where he can't lick or scratch it, so there's no risk of him making it worse. As of right now, it's completely clean and not inflamed or infected.