Thanks for your query.Based on the facts that you have posted it appears that you have increased frequency of urination and sensation to pass urine .
This could be due to infection of Urethra
The fluid that you pass during masturbation
is not a semen but excessive secretion of Peri Urethral Glands located in Urethra. This secretion acts as a lubricant and facilitates free passage of thick semen during Ejaculation.
Take some antibiotics like Doxycycline for 10 days.Get prescription of this medication from your family Physician.