Yup everyone goes through that at one point or another. Often its because we are such a bad "self judge" :) We look at our favorite musician and we say to ourselves "oh man I want to do that, this so cool !" we work to attain it (obviousbly thinking we are gone be good when we achieve it) but has we start to get the hang of it there's something else that we want to achieve and we say "oh man I want to do that, this so cool !" and we can go on like that for a long time always thinking we suck because at that point in our life we cant do what our "best"/favorite musician can do.

Where always practicing to get better in the futur but it dosnt mean we suck in the present.

The best thing I think we can do is to record ourself as much as we can. Try it. Record yourself playing a song you can play well, a day's practice, a jam with a buddy...anything really. Dont be afraid to hit record. In 3 months time when you listen back to your first recordings you will go "ohh wow ! I got a lot better ! ".

There's actually some songs/jams I recorded last year that to me sounded awesome and I was proud of. I took a listen to them recently.....my oh my did I grow as a musician since then lol.

Just make sure you have fun.