I dont think it's ever too late to wash a wound. If it reopens, it needs to drain. Fresh, bright red blood is actually a good sign for healing. I would absolutely flush it with chlorhexidine or something similar, it's not painful. Dawn dish soap is safe to bathe her with. Then topical antibiotic. I dont know what otc is safe for pain management, you should check with a vet for that. Poor girl!