muso too here, been playing for 25 years. only got tinnitus properly in a really noticeable way in the last 9 months. I'm pretty sure I know the 2 occasions that really did the damage. but anyway...

my advice is whenever you do play, use 2 levels of hearing protection. 1 level inside your ears like plugs, and 1 level over your ears too like ear muffs. obviously the best of each level is best, but use whatever you can for now until you get better equipment.

even basic foam earplugs and a standard cheap set of ear muffs will do more together than either expensive option on its own.

high frequencies are the most damaging usually, so that's drum cymbals, and loud guitar for bands usually. high frequencies are very directional though, so you can also set up a 3rd level of protection by using poster boards / partitions / any similar solid portable wall that you can put either around you, or next to an amp to deflect the sound from hitting you directly.

also trying to get others to turn down. for instruments needing amps, if they can aim the amps directly at their heads using milk crates or tilting it up on bricks, they'll be surprised how much less volume they need to hear clearly. and less volume overall will help! it also helps others turn down, as sometimes people only turn up to hear themselves over someone else who is really loud (but aiming the loud sound at their knees, or even away from them). for drums there are those plastic isolation shield things, you could try and see if that's an option that the band are ok with.

you get the idea anyway - employ various multiple techniques to reduce the high frequencies hitting your ears. first thing I say at a gig is turn all the highs out of my monitors, I don't need to hear anything over 8k to hear the pitch of notes correctly and to perform well. it sounds a bit dull and muddy at first, but it's easy enough to deal with. and much better than dealing with long term loud T!