The advice in this thread is pretty good - Ruling out the obvious by seeing a doctor and a therapist seems like good advice. Sounds like you're under a lot of stress. When you're under stress even the simple things in life gets many times harder.

Once you've cleared that. I always recommend meditation and exercise. Plus reading. And writing. It's tough when you're under stress to see how you can fit it in, but it makes everything run so much better.

At 33 you shouldn't really be having these raft of issues. However, if you're anything like me, you've spent the last 10 years running 1000%, hacking till 2am regularly and generally not taking good care of yourself. Stuff that you can push yourself to do at 18 gets harder and harder each year.

Finally. You're right. Web Development is crazy at the moment. It's one of the fastest moving areas in tech at the moment. I don't know how anyone can keep up. So don't overload yourself with expectations.