Soreness On Tip Of Penis. Diagnosed With Hyperhydrosis. Cleared Of Yeast Infection. What Is It?

Question: My 15 year old very healthy son started complaining of excessive sweating on hands, underarms about a year or so ago. In Dec, he was diagnosed w hyperhidrosis. He began using Certain Dri (special under arm deodorant) which helps. He also used Xerac AC on his hands. In early Feb, he began complaining that the tip of his penis is consistently sore and very sensitive if anything rubs it. So he wears tight underwear, but this only provides minimal help. His pediatrician has seen him and has nothing to offer in terms of relief. He saw a urologist who did a procedure to examine him internally and the urologist said there is no health concern. But my son continues to experience soreness on the head of his penis. Also, I have noticed that his hair is starting to thin considerably. I know he was tested for bacterial infection and given Cedferin (sp?) antibiotic just in case. I know he is not sexually active. He has started taking probiotics, just in case there is a yeast infection, but that has provided no relief and I was told by urologist that there is not a yeast infection. I read online that one case of sore penis lasting 2years was successfully treated with botox injected into prostatomembranous junction. He drinks a lot of water each day. He is otherwise healthy. My Internet research makes me question possibility of thyroid problem, pituitary tumor, lupus, hormone disease. Is there suggestion you would make considering the above symptoms/medical history?