Three things seem to help me somewhat:
Nupercainal cream has a topical anasthetic in it. Apply it liberally 15-20 minutes before using the bathroom, if time allows. It will numb the sensations a bit.
There are homeopathic suppositories and tablets called Avenoc, made by Boiron, available in some health food sections/stores. The suppositories are more soothing and lubricating for me than Prep H, and I think the tablets actually make a difference. (Homeopathy doesn't work equally well for everyone, but it usually helps about 80% of users.)
Use a stool softener daily until the flareup subsides; it will give your poor little orifice a chance to heal. Taking extra fiber, like Metamucil, may also help. I also seem to get help from Benefiber added to a drink every day.
Also, my daughter JUST gave me a sample packet of a topical cream called Calmoseptine. I've only used it once to soothe the area after a traumatizing movement. I was pretty amazed at how cooling it was. I haven't seen this before, but she says it's available over-the-counter.
Wishing you the best possible outcome. You've got my full empathy.