Hello, welcome to health care magic. I am Dr Alok Sinha, MD Psychiatry from India. I will try my best to answer your query. It appears that you are having dissociative/ conversion reaction. This type of illness occurs if there is ongoing intra-psychic conflict in mind. Let me describe you in simpler terms. It is clear that you have lot of anxiety of getting some sexual infection because of your recent sexual exposure. Further your subconscious mind is fixed with the fear of some discharge coming out from penis, thus making you experience some wet sensation. It usually happens if there is underlying conflict in mind (like your subconscious mind knows that indulging in sex is prohibited, still you commit the act and later on your mind punishes you with some motor dysfunction or abnormal perceptual experiences). In an anxious state the mind fails to get assurance that everything is OK and keeps on worrying excessively. As you told, you could not find any discharge, you are found negative for STD and no any other symptom of STD till the time, except a wet sensation at tip. So actually nothing is wrong except wet sensation (perceived). This perceived wet sensation is curable. I suggest you to consult a psychiatrist who may put you on psychotherapy and /or some medicines to get you cured. I wish you all the best.