My son has lactose intolerance so we give him nusobee he is 3 years 3 months from past six months he get fever with in 40 days some time with in 15 days very often early he was diagnosed with urine infection but we given him medicine so I agai checked his urine routine and culture which was negative and ultra sound also done which was ok .i also give him medicine medicine for urine infection urine for 3 months so that he should not have this infection again .i give him tonoferon for iron I got tested his thelsymia when he was born because iron was very less report was negative. So please tell me reason why he get fever so often otherwise he is very active he plays runs in fever also .i just give ibugesic plus and antibiotic and he will be fine fever stays for 3 days only. So should I ger his blood test done and if yes which test I should do .