Are you still experiencing the swelling? It's possible/likely that the prednisone was instrumental in the change in your TSH, which can be affected by a number of variables.
I would wonder, however, if you've had anything other than TSH tested? TSH is, typically, only useful for diagnosis, but should never be used as the sole determinant for diagnosing a thyroid condition or prescribing medication dose. You should also have Free T4 and Free T3, every time you have a TSH test. If you've had tests for FT4/FT3, please post the results, with reference ranges, so we can a better picture of what's happening.