I can't stay happy, things can be going so good then my body starts rotting from the inside and I start having awful thoughts in my head. I feel awful even typing this like im a desperate disgusting human why should other people reply to me but I am desperate i just wish to connect with other humans anything would be nice.
I think the fact you are aware enough that you are having these thoughts despite good circumstances is a start to dealing with them. I'd strongly suggest talking to a therapist as it's hard to gauge the extent of your dark thoughts.
Outside of therapy I'd look into a few different things that could help, they've helped me. Daily gratitude journaling, at the beginning of each day or at the end of the day try to write down three things you are grateful for. Keep doing that and you start to rewire your brain to look for the positives around you each day and you start noticing/focusing on the negatives less.
Mindfulness meditation and other practices can also be a great benefit in increasing contentment if not "happiness". Learning to be aware, acknowledge, but not dwell on your thoughts, particularly the darker ones. It's not something that came naturally to me, it took a long while and a good amount of practice but it does eventually start really helping.
Lastly I'd leave you with a thought on happiness in general and that optimism/positivity is a choice. And it doesn't mean that everything will always be good in life, the same amount of bad things will still happen, but when you choose positivity it means looking for the upside to things, and not dwelling on the negatives for which you have no control. If something is bothering you ask yourself, Can I fix this? If the answer is No, why worry about it as it is beyond your control. Doesn't mean to ignore things, but dwelling on that which is beyond your control is a futile exercise.
I wish I had more I could say, or something that would make you happy permanently but it is a process, and it is something that takes work.
