Yes, the hydrocortisone can in the long run make it harder to heal if it is overused because it thins the tissue. That is what my CRS told me last week.

I, also, had pain when bending over, but I could definitely tell it was in the anal area. I started bending one knee while kicking the other leg out behind me. Helped a lot. Until we have a sore spot, we don't realize how simple movements can pull on large areas of the body.
If you can't isolate the pain to your anal area, I would definitely see a doctor about it, sooner rather than later.

One more thing:
I have not been diagnosed with fibromyalgia as I think you have, but I have many of the symptoms. Found on the internet that exercise helps and my physical therapist confirmed that. My husband and I began walking two miles a night and within days, my aching was so much better. My fissure was also slightly better. Years ago, a doctor told me walking moves fluids around in the body and might help the bladder pain I was having.
Are you able to walk?