Lots of things can cause hearing loss. a high fever is one of the worst things you could have had as a child. think measles or mumps. A severe infection also.
Since I was one of the biggest guys in my unit I got to carry an M60 for several years, trained on mortars and 90mm recoilless rifles only hearing protection was the filters off cigarettes.
Driving trucks with windows down and air blowing in your left ear really causes a lot of trouble and the left ear seems to always have the most loss.
Tinnitus is a brain thing along with all hearing loss and there is no cure for any of it.
I have an MRI scheduled to see if I have any sist on my brain that could be causing some of it, if they are bad enough they could be removed.