What Could Be Causing Persistent Daily Itching On My Scrotum And Shaft For Over 2 Years?

Hello, I have had itchy balls for over 2 years, it changes in terms of severity but is always present day to day. The itching is always on the lower anterior portion of the shaft or just below on the balls. They sometimes become red, itchiness changes day to day but never painful. Getting naked and into bed alleviates the itch, I am never itchy in bed only when wearing clothing. I have been tested for STI s and am negative, I have tried calamine lotion, hydrocortisone 1% and antifungal cream to not much effect. I wash 2-3 times a day as I go to the gym, I use talc everyday and this helps prevent itchiness sometimes. I am at my end now trying to solve my issue as it is affecting my life, and is unprofessional to be itching at the workplace. I am now trying non-bio detergent and different underwear to try to solve my issue. Many thanks,