What Causes Foot Pain With Intermittent Fever In A Child?

hi, my 10 year old son has been sick on and off this winter. he has had a cough, fever (mid to low grade), foot pain to where i have been doing hot foot baths and even went and got him new shoes and inserts. he has been diagnosed with pneumonia, sinuitis and is now on his third round of antibiotic. he still continues with the foot pain and the fever comes and goes??? he has me stumped.. my doctor states he may not like school that is why his feet hurt but there is no way you can fake a 102 fever... any thoughts? sincerly worried mom.