Allerigic to ibuprofen?

My dermantologist put me on accutane, prednisone and ibuprofen. I've been on them for about 2 weeks and the past few days I've been breaking out with these huge rashes all over...my arms, my back, my stomach...very itches welches that seem to be the hives. I'm not sure what could be causing this, do you think I'm allergic to the ibuprofen?