As your all reports are normal so there is only possibility of having some local infection on glans penis
.Some time poor local hygiene may lead to collection of smegma
on the glans causing irritation and chronic infection on the part giving itching type of pain.
So clean the part by averting the skin on glans daily while taking bath.
Take plenty of water.
As urine and ultra sound
reports are ok,you do not worry.
O k AND BYE.