Have you ever contacted Tinnitus UK for advice?
Has a GP ever referred you to an ENT or audiology? You need to see one to rule out any medical conditions. I know someone with severe tinnitus and she wears some sort of gadget in her ears that helps mask the noise.
See a different GP until you feel that are listening to you.
I have had tinnitus for 30 years and the sound level is very manageable now, but I have been to hell and back with it. I suggest that you get help for your anxiety because that will make your perception of the noise level worse, that then causes stress, and so the spiral continues.
I found when it was bad to learn to breathe deeply, right from your stomach. Focus on your breathes, slowly and deeply. After a few minutes I would feel the noise level start to lower a lot (a support group taught this technique).
Be vigilant with reminding GP’s that you cannot take any prescription that has a side effect of causing tinnitus - there is surprisingly quite a few like Naproxenetc. I always read the leaflets thoroughly and the slightest mention of tinnitus - no matter how small the side effect could be - and I refuse to take it, contact the GP and ask for something else. Don’t take your GP’s word for it that it’s fine - check yourself.
Try going out for a short walk initially - small steps to getting yourself out of the house. You may find the distraction of the various noises helps to mask the tinnitus, and a step towards learning not to focus on the tinnitus as this makes your perception of it worse. When you are doing little other than focus on how terrible it may feel, and then your anxiety spikes, and so the cycle continues.
Please do seek help and support - you don’t need to be living like this. Ask your DP to come with you to the GP for support and to make sure they fully understand that you need help now.