My son had rheumatic fever when he was 11. It took a long time to get over the physical pain from it. He was able to go back to school, but had to come home and rest every day.
We did have a rheumatologist in on the treatment. He, too had to take penicillin for several years, but now only before, during, and after dental work. He is 32 now and it is as though it never happened. We will be praying for your daughter.