lol mate that's a corticosteroid, nothing like AAS. Probably has just as many side effects though. I was on prednisolone for an intestinal thing and had to stop after two weeks, side effects were unbearable.
If it's just a minor problem I suggest seeing a different doctor and weighing up the pros/cons.
From what I remember any weight gain is just fat or water retention or something. I don't know, my weight didn't change with prednisolone.