School issues

Ok so I currently have had to leave school multiple times for a unknown allergic reaction that come with blistery itch hives. The first day last Thursday I had to take Benadryl and go home. Friday it happened and I couldn't take Benadryl. Saturday it happened again and we went to the doc to get prednisone. That didn't help. I got them again Sunday while at church. Monday I got them really bad again in school and had to leave for a doc appointment that they squeezed me into. I got a shot for that and now I'm having a yeast infection?!!! Does anyone know if these could be connected or what I can do to get rid of the yeast infection? I'm in so much pain and can't leave school or anything for it because I have a volleyball game today and I couldn't play yesterday because I left for a doc appt. I really could use your help!!