My 2 Yr Old Grandson Has A Temp Of 38.5

my 2 yr old grandson has a temp of 38.5 stomach pain head ache and vomiting also ballitis in the penis he has only finished antibiotics 5 days ago and is poorly again he also suffers with reacurring chest infections and is on antibiotics approx. every 2 wks to 3 wks what could be wrong as I don't feel he is getting checked properly