My Grand Daughter Was Diagnosed With Strep Throat About 3

my grand daughter was diagnosed with strep throat about 3 weeks ago - test came back positive but she had no sore throat or anything else - put on antibiotics - went back because fevers were low grade and she was complaining of earaches, doctor noticed fine rash all over her body - diagnosed with scarlet fever and put on another antibiotic, then she started having joint pain in hips and could not stand because of pain, went back to doctor, another antibiotic. has been vomiting, not eating or drinking, running low grade fevers for 2 weeks now, still has pain in wrist and hips, elbows and has several headaches a day - according to the 3 different ERs we have taken her to they dont know what is wrong with her - she has been admitted twice but discharged the next day becasue they didnt knnow what was wrong - they suggested an infectious disease doctor - her blood work that shows inflammation was 1.6 2 weeks ago and just this week it was 9.8 - what can the problem be that the doctors dont know what to do and just keep putting us off.