Well, without a clinical evaluation it would be difficult to determine the cause of your symptoms. Possibilities that may need to be considered include infections, inflammations trauma, erosions, growths/ masses, neuro-muscular issues etc. With clear usine tests, infections are almost ruled out while inflammation is a high possibility following a surgery, which is likely to settle with time; while other causes would also need to be considered. I would suggest getting this evaluated by a urologist for an accurate diagnosis and appropriate management.
Hope this is helpful.