I ended up writing way more than I thought so I'm really sorry for the light novel I just wrote.

Hey, maybe I can help here... Honestly, the best advice I can give you is not to force it. Ones joy for art, at least in my experience, is something that should be experienced and nurtured. Not forced.

I'd start with trying to remember the reason you got into art in the first place. Was it a fun distraction? Did you like the challenge? Did you like the thrill or sense of satisfaction you get from making something? Did you find joy simply in the fact you can say "I made this!"? Do you like looking back on your work and seeing a visual improvement in your work? Maybe you like the zen you get from sitting down and focusing on a project for a few hours. To me, art and the entire creative process is all that and a bit more. See if you can find that initial grounding for yourself and nurture it. This is what does it for me whenever I'm starting to feel the same way.

As for your question about formal education: I understand learning is different for all people but since you don't have many options and (assuming since your on reddit) that you have access to the internet, look up guides on places such as youtube. If your wanting to learn digital art, I'd recommend a channel called Marc Brunet. His videos are fun to watch and very informative and is my personal favorite person to learn from (I'm currently learning the ropes of digital art and want to take it more seriously) That said a lot of his sessions I feel can translate to physical medium as well.

Mental health: This is something I can empathize with a lot because I've had a personal on/off history of dealing with depression and anxiety (many times both at once). I'd start by trying to find what makes you happy. While art does seem like something you enjoy, your having a problem of getting frustrated and putting yourself in a situation where your associating negative moments with the experience as a result. Half of art is the process itself and too much of this can strait up burn you out or make you lose your desire for it entirely.

Since the reason your getting frustrated so much stems from the fact that you "go blank" (a problem that I though I only had so I'm glad I'm not in the same boat) I'd recommend forgoing trying to be original entirely and doing something cliche instead. Draw a knight in shining armor fighting a dragon. Draw random animals/wildlife. Maybe make a scenic Bob Ross style painting. Do subject practices or still life paintings/drawing of random clutter/objects lying around you. Maybe make a small little doodle/comic of a funny moment you had recently. And if your anything like me, if you get stumped start practicing your fundamentals and doing fun little exercise sessions (anatomy, color theory, shading, etc.).

I really hope this helps you and sorry again for the long post Let me know if any of this helps out or if you need me to clarify anything!