I second this. Without good health, everything else is so much harder.

So I know unwanted advice should not be given, but I can't help writing my little version down. What has helped me fix my anxiety, concentration and procrastination issues is vipassana meditation - but you need a certain level of strength, it is not an easy path by any means. It will probably not help you as quickly as you need right now. I wholeheartedly recommend it though for the long run, once you have the bandwidth. It has the potential to change your life for the better and offer profound self-insight, if done correctly.

Perhaps try meditating? It's works for my negatively racing mind, usually. My thoughts are clouds, the state I wish for is a blue sky where clouds that appear are quickly dissolved or blown away. Try the trial of Headspace. I think they nicely hit the balance of not trying to force it, just never stop trying. An empty mind can feel very nice.

I never sunk as deep as you though. I get weeks of "stuck on negative issues in my life". Daily meditation of only 10 min already seems to help, I am by no means an expert by the way. Headspace helped me and when I try meditating now, I hear the voice of the Headspace woman (you can also select a man) talking to myself. When I feel bad again I may sign up for the service, but as said the 10 part trial is nice already.

Edit: 2 times meditation advice in 5 min ;) As below, it may not help very much very fast, still, after trying to actively calm my mind 10 min I usually feel better already. Even when it "fails" for 9.5 out of the 10 min.

No relation to Headspace btw ;)