This will sound crazy.
It might actually be crazy.
I, like everyone else, have been through the same thing. In the past, I did the same things most people do, and went back to basics, starting with my bridge, stance, etc.
What it really boils down to, is lack of confidence in your shot.
Now I have come up with a routine of simple shots to restore my confidence. At the first sign, that I am not trusting my shot, I go through the "routine". The first thing I do is remind myself, that it's the stupid shit again. I think back to what I have done in the past, and that it has always come back to lack of confidence. Then I believe myself on that point. The next stop is to shoot a couple of simple shots that are always the same. I will put an object ball on the rail, just on the far side of the side pocket, and the cue ball on the head spot. I will then shoot it in the corner pocket, without regard for cue ball position. I will shoot the shot without thinking about anything. Repeat 3-10 times with out a miss. If I miss, I will laugh about "how bad I have it this time" and start over. Then I will move the object ball out 1/2 a spot and do the same thing, until I have worked out to the middle of the table.
I simply let myself shoot the shots, without thinking, until my mind is clear, and I can laugh at myself about trying to screw my mind up with the confidence boogeyman.
The bottom line, is that the one thing that screwed up your game, was the lack of confidence. The sooner you let that go, the better off you are. What I do, is the best for me, but I suggest you come up with your own "confidence routine". For the next couple days, shoot the routine before you do anything else, and then laugh about how that boogeyman tried to nail you again. Yow will know when the moment is past.
Yes we sometimes goof up and change our mechanics, but 99% of the time we just "change our confidence".
Good luck.