<s>[INST] hi, my 7 year old son came home from school with fever and headache. Later on he started complaining about his legs being sore, from behind his knees downwards - he then started crawling on his knees which worried me. I remember him also saying that his neck was hurting lastnight.  I took him doctors, but they said he was ok.  I am still worried. [/INST] Thanks for consulting in Healthcare. In case of your child some reactive arthritis or juvenile rheumatoid arthritis, symptoms of intoxication from viral infection, streptococcal infection. He needs to be deeply examined by blood test, antistreptococcal antibodies, rheumatoid probes, IGM, G CHL., Myc.trachomas, uric acid. He needs in antiinflammated therapy with nonsteroid-give him ibuprofen syrup at least for 5-7 days. You should visit rheumatologist if you will not see improvement </s>