You should see your gynecologist. You may have endometriosis, which is excess growth of uterine tissue. I had it. Same symptoms. These days it's a minor operation.

I could be wrong, of course, but see your doctor to rule it out.

You're in my thoughts as a fellow sufferer of "the monthlies".

Edit to add, yes, it could be menopause. I'm not an expert. Just please see the doctor.