On christmas day I had a terrible sore throat. It's gone now, but my allergies have gotten worse and I can barely breathe. Medicine? I'm on prednisone

M.D. visit. Please see comment listed below. I would advise seeing a physician right away, since you are experiencing difficulty breathing. They may give you additional medications and/or a higher dose of prednisone.
As above. If u feeling that way u need to see your PCP for evaluation and treatment. Good luck.
Reactive Airway. Your sore throat may have secondary to a viral infection. Viral infections typically cause post-viral bronchospasm even if one does not have a history of asthma. The bronchospasm can become life threatening in an asthmatic. Hence, discuss with your doctor.