On the sitz bath idea-

Gentle saline soaks or baths can help a lot, too. Mix 1 cup of water with 1/4 tsp salt and warm it up in the microwave until it's body temp. (35 seconds in my micro)

Put it in a canning jar or cup with the right size opening. Hold the jar to the sore, and kinda suction it into place. (you might want to be lying on your side) Hang out for about 5-10 min with the warm salt water in contact with the sore the whole time.

don't try to scrub it or wash it or anything. Just let it soak.

You can also drip the saline over the sore for 5-10 min. That uses a lot of saline, but can be a bit more effective if you've got yucky stuff that you want to wash off gently without irritating the tissue underneath.