Has anyone heard of becoming allergic to xanax and klonopin after being on them for years lately whenever?

i take them my lips go numb my neck feels like its thicking,and my cheeks feel funny..and yesteday i started getting a rash in the top of the crack o fmy rear and today it has aa blister inside the rash.I went to a medical dr last week and he said i am not allergic to them,im tapering off the xnax and i dont knw if that is part of the problem..i was also on a short dose of prednisone for 4 days 20 mgs amd 10 mg for 1 day all this started after being on the prednisone,but i was only on it 5 days..i was on klonopin from june 07 till jan 08 and tehn put back on xanax in feb 08 and back on klonopin in april 08.after i am done with my xanax taper i willl taper offf the klonipn.but im so scaed for some reason i have become allergic,and i know i cant stop these meds cold turkey...anyone ever hear of anything like this,,could it be me being so afraid causing these reactions?