Prednisone question for a friend

I have a friend, who doesn't have UC, but was presribed Pred for another health matter.  I'm not sure what her initial dose was but she did do a taper until eventually she was off it.  Since she had stopped the pred, she broke out in a rash all over her body.  Can pred withdrawal cause a rash?  If so, what is the reason behind this?

I already went over all the possible causes for the rash and she couldn't think of anything new she had used or tried.  It just seemed weird that she would develop a rash right after stopping the pred.

Here's one wacky idea:

Let's say that a week or so ago she got a rash for some completely unrelated reason -- an allergic reaction to some new laundry detergent, for example. The prednisone would effectively treat that rash. But then you stop the pred and it starts to show up. SO... it could be completely unrelated but showing up now because she stopped taking the pred.

Here's a second idea:

I got a rash on my face from stopping Pred, but my dermatologist diagnosed it as a skin condition (perioral dermatitis) that comes from stopping using steriods. Could this be something similar?? Maybe.

Third idea:

I used to get wierd rash like bumps all over my body for no reason... but usually just where my clothing was touching tighter -- like waistbands. It eventually went away and I could never figure out what caused it or made it go away. It's called "pressure urticaria" -- hives caused by pressure. Maybe a condition like this was just waiting "in the wings" and was under control naturally. BUT using the prednisone makes your own cortisone (or cortisol or whatever, I can never remember) levels drop. Pred surpresses your own ability to produce natural cortisone (or whatever). So it could have come up now because her own body can't keep it in check. I took Benadryl for the rash/hives when I needed to and that made it better.

I'd say two calls might be necessary: the doctor who prescribed the Pred & a dermatologist. But be sure to have the dermatologist to consider the steroid angle. My first dermatologist never made the connection!