My 22 Year Old Son Is Away At College And

my 22 year old son is away at college and has himself very worried. he had a uti about 6 months ago and was treated for it. now for the past few weeks he has painful urination and says he noticed a cloudy penile discharge. he went back to the doctor and was tested for another uti. that test was negative. he has himself very worried can you help with advice.