Hello fellow suffering creative mind.
I am currently dealing with this. But I try to see my creativity as the thing that it is. A vital function of my mind. It is basically like digestion.
You are probably sensitive and perceptive. So you need to get some stuff out of your head. Deal with the things you pick up. Digest. So the things your brain produces don't need to be good. If you feel like you're producing shit, than by all means, get that shit out! Allow yourself to be bad.
It is not your job to please anyone, not even yourself.
Woah, listen to me all preachy. I am still struggling with this. But I have worked my way into becoming somewhat callous about this whole creative thing. And it feels amazing. Also: this is the only way I'm gonna do something worthwhile. Of course I wanna make great art and it's good that I am critical about the things that I do, but if my critical mind is keeping me from working, than it doesn't do it's job right.
I am currently working on a book. I try not to think, judge or hold myself back with whatever it is I feel like writing. It's a project. The content is not important, I just go wherever it takes me. It's fun. It's also tough. But I defininately encourage you to find the right mindset to give yourself some freedom for "failure", especially when failure is so goddamn underrated when it comes to creativity ... when it comes to life actually.
I think what I am trying to say has been said before. And better. I collected a couple of links on the forums, that deal with various mental issues: http://mentalpod.com/forum/viewtopic.php?f=34&t=7355&p=13837#p13837
There is a section on creativity. Get inspired. You're not alone with this. In fact the greatest minds in art and science struggle with this. So I hope this helps.
Take care. Sending some good thoughts your way.