Definitely noise exposure. Used to DJ without ear plugs (ouch), however very quickly got a nice pair of custom fitted -15dB earplugs. To this day I still wonder why the person that sold them to me didn't recommend me to take the -25dB. I already had a very tiny amount of T by that time but it was only noticeable when it was absolutely completely silent so I didn't really think much of it.
It's hard to say why it suddenly got worse 5 years later, but I think it was stress. Possibly also more noise, as every now and then I would be at a graduation party or something without earplugs, not expecting the music to be very loud without any reason. Since then I never leave the house without earplugs, not even to get groceries. You just never know when you might need them.