brother its psychological. its otherwise quiet normal issue. its lubricants drops, which are naturally created in the body to ease urination process from process. as without such lubrication you will be feeling hard while urination. Allah's action has logic in them.
be natural. adopt natural foods. avoid junk items, coke pepsi etc. use pumpkin (kadu) as much as you can. its sunnat as well and increase your libido and diminishes infertility rate in male. second, exercise daily. third offer prayers.
dont visit any hakeem or homeo doctor, they will definitely advise you steorides, which ultimately fail kidnies and only net result is destruction. consult professor arshad otherwise on telephone, he is very nice person, rather angel in this earth.
his contacts available on this site.