I have a 12 year old grandson who was diagnosed with canker sores, well he has only continued to get worse. He has run a fever for 4 days now, and the inside of his mouth is full of blister type sores, he has been on a Z-pac and was also diagnosed with bronchitis, I am a nurse and I can tell you he does not have bronchitis. I don t understand the fever, headaches and the spreading of the blisters in and on the outside of his mouth. Please help