I'll admit i use to like powerchord rock and for most of my time playing the guitar i have been wasting my time playing that kind of music. But after a while I wanted to learn how to solo.

So I started to learn some scales, I was already familiar with the blues scale(My personal favorite) But i got accoustiomed with a few more.

As I practiced them I got the hang of it and began to play em' decently fast. However the next couple days i like, well, lost it. The scales sound very sloppy. It's like I kinda lost my new found skill overnight. Has this happended to anyone?
Sometimes when I pick up a guitar i feel as if im ;playing really bad. Usually I just leave it for a while and come back later
It's usually a cause of lack of cocentration on your behalf - just playing the scale, over and over again without any real conviction.

Most of the time you'll play your scale runs one day, just for the sake of it and retain little of what you learnt the next day - that's just how the human mind works. If you don't concentrate or aren't aware, your (you) fingers won't remember.

Compare it to studying... if you study for 3 hours without concentration, how much are you going to remember? Very little. If you study for 3 hours with concentration and awareness, you're going to be more prone to remember what you learnt - same applies to guitar and your fingers.
I agree with Johnljones. but try this as well. listen to songs, any songs, and play a solo over an appropriate part. you could even try to harmonize with the solo on the track.
The most important bit is to listen to different styles and find what suits you, what you like and to make your own sound