I went through something similar. The biggest surprise for me was that hearing aids are usually tuned for speech clarity, not for music. As a result, guitar can sound overly bright, compressed, or just unnatural at first, especially electric guitar with lots of harmonics in the frequencies being boosted.

Definitely talk to your audiologist about a dedicated music program. Many people have much better results once the noise reduction, speech enhancement, and compression settings are adjusted specifically for music. In my case, that made a bigger difference than changing amp EQ.

I would avoid simply cranking the treble on the amp to compensate, as that can end up making the overall sound less balanced. A custom hearing-aid program designed for playing and listening to music is probably the best long-term solution. Give yourself some time, too—your brain is adapting to hearing frequencies it may not have heard clearly for a while.