Nancy,
For what it is worth, I never took steroids after treatment. I did take the one blue pill on the three days of treatment (Decadron), but that was it.
I had my six month MRI here in Portland, and mailed it to Chang's office. Ami, one of the medical support staff, called with his comments. We discussed that I am still a candidate for swelling issues for another 12 months, and I asked about steroids. She said that it is rare for post treatment swelling to cause any permanent damage; the prescription of steroids is mainly to address patient comfort during the swelling phase, and is optional.
So you don't have to take steroids. Even if you do have swelling, you may find that Ibuprofen is sufficient to manage it. Since you have a negative reaction to steroids, it would make sense to take Ibuprofen (or other anti-inflammation medicine) and grin and bear it, should the occasion ever arise. I did that during a two week long phase at about 3 months.
Steve