Hey. I also spent time in Kandahar. In 2008. My ears ring constantly. It seems to be getting worse too.

I keep a sound machine running all the time in my room. This one specifically, https://www.amazon.com/dp/B076F2JKYC/. I like it because it's not playing audio. It's an actual small fan. On real bad nights I wear a pair of headphones. I have a subscription to the Tide app. There's a couple good sounds that help the ringing just sort of blend in.