I think you should give this idea more thought. The situation you find yourself in is not uncommon among high-functioning ADHD persons, and your life can truly get a whole lot better with a bit of therapy and medication.
While you're at it, you can use the therapy as an opportunity to probe why your job was such a bad fit, why you ended up in it, and how you can recognize and avoid such work environments in the future.
It may be a good idea to leave your current job, as others have suggested, but I think it would be quite dangerous for you to do this without also exploring the above more forthrightly. My advice, as someone who has dealt with a similar burden: don't overthink this. Just go to your GP, tell them you are suffering, and tell them you would like to investigate ADHD therapy. Approach this with a calm curiosity. You are in control.