What do I do if I’m feeling mentally sick?

I’ve tried new hobbies (including gym) but it’s only worked for a bit. Try improving myself over the years but my mind now feels so lost. Making new friends, ha that’s funny… can’t do that in real life or online and it’s my fault entirely. Tried feeling better about myself, didn’t last. Heck really I struggle to remember any good memories because all the shit I’ve gone through (not just the above, so much more that nobody knows) and all my current hobbies, they don’t feel the same. I’ve really tried to live past my pain all these years whilst the pain adds up but I just… barely feel any happy anymore genuinely and I feel sick mentally. I told my friends a tiny bit of the shit I’ve went through, but they don’t really help. And I hate thinking about my life in the future too, I’m not hopeful for f*cking any scrap of happiness.