What Causes Constant Stinging Pain All Over The Body?

my 5yr old son is suffering for the last 3 or more wks with stinging pain all over his body, mainly joints and the last few days in his penis, he has swollen glads in his neck and stomach, gets bouts of tummy pain, weakness, dizzy and temp up and down, was given antibiotic 3 wks ago but condition is getting worse, we are waiting to get hosp apt to get bloods down, his blood sugar levels are fine and his urine sample didn t show up anything either. he is fine one minute then falls to the floor with a pain of stinging sensation that will last a few secs.