I don't know what your exact situation is so the suggestions that follow may well have already been tried. Obviously, disregard them. None of what I say is magical cure for anything either, and is not meant that way. It is more like suggested weapons in an arsenal. An experiment you can run on yourself. Because standard responses to mental health issues are frankly utter garbage. Because rarely is it explained why this may help and be worth a shot. Feel free to roll your eyes if you like. The choice of what you do is ultimately up to you.
My first suggestion is to simply get a physical screening. The horrible invasive variety that no one wants to do. Rule out any potential biological issues that may be impacting on your mood. Things like onset diabetes and thyroid issues. Lots of mood deficits can manifest as a first response to physical issues. A lot of times this vital step is missed entirely if you present with mood issues alone. If that has happened to you then you are being failed when time could be crucial. Not trying to scare you, but it is fact that brain diseases also cause wild mood swings and oversensitivity to stimuli. If you are being fobbed off as just anxious this gets lost in the medication grind.
Lack of various vitamins can also be pretty damaging to mood especially if you stay indoors most the time and eat crap because you are too depressed to do otherwise. All of it can manifest this way. Only a physical screening will rule all this out.
My other suggestion is to maybe look into a life coach. The reason I suggest this as it is a pretty unregulated field. There is less red tape to contend with. They are not in any formal position to medicate you either. They also have a tendency to focus on the whole of a person and are more proactive and practical about it. Being the motivation you may well not have and helping you get things done. It is also just beneficial to have someone in your corner you can build rapport with that is not driven by target culture. Sure you are paying for the privilege but that is just life. probably wouldn't mention suicidal ideation though. Societies laws still apply even if they don't have a formal policy. BUt they maybe able help keep you motivated as you run your self experiments from the advice given.
You have before referenced feeling overwhelmed by stimuli. How intense is that for you? Do certain sounds make you want to smash the offending object? When you are in a crowd is it a feeling they are judging you? Or is it more a feeling of it being like chaos and being crowded and you can't handle it? Do you want social company but under your control, or do you honestly prefer being alone?
What are you most paranoid and anxious of? Have you noticed a steady decline in your concentration? If you have been on psychiatric medications for a while, they actually can damage short term memory and concentration over a long enough time. But if something biological is at work that can also do the exact same thing. Do you remember a time when you did have good concentration? Or sport gave you consistent enjoyment?
Lastly, I would consider Meditation. A misnomer is it is trying to get you to think about nothing. There are different types out there. I am not spiritual personally. I got benefit from a particular variety that focuses more on the body. My job was very stressful and it helped calm me down after wanting to set soulless bureaucrats on fire. That is my experience though and we are all different. I will link it here and maybe you could have a crack at it. At worst it is simply annoying. No harm in trying though.
This is a pretty detailed article on meditation and takes a rounded view. So you can make your own mind up.
https://endpoints.elysiumhealth.com/the-science-of-meditation-1442df86a5fb
Wish you all the best in your self experiment. I hope you can get some relief.
