I've posted about
it before. I had the same - more symptoms around the first day of my period. But it started after I was on Prednisone for 2,5 months in Spring last year. The first period just a three days after tapering Prednisone was like a nightmare. I was terrified that everything was coming back, so I understand your worries
Advice from me? If you are on Prednisone just maybe don't taper during the period. I know that sometimes being on this stuff a day, three days longer can freak somebody out, but why taking a risk? If you just can postpone lowering dose for a couple of days.
In my case, I took strong pain killer and returned on prednisone for a couple days, small dose, as my tapering was going smooth. Don't know if hadn't panicked too much, but the most important thing, I haven't flared! Since then (Aug 2011), every month (I was on mini pills as estrogen gave me a terrible headaches) was less severe but I had more symptoms. And they got to normal after the first, second day of period. With or without suppositories.
Now I have Mirena, for a week so not too much experience with this stuff so far. Really hope it will stop my periods at all