Suggest Treatment For Sticky Penile Discharge And Soreness In Penis

Hi, I am 33 years, height 5feet 9, weight 73 kgs, I am having a small problem with the tip of my penis. It seems a bit sore all the time. i have checked for all STDs and the results were negative. My Doctor tells me that i may have hurt the nerve endings and it will recover anyway. But for this period I always find that the tip is stuck with the underwear and have to apply water before i can take off the under wear. Can you please suggest