Do you mean skill that goes astray, or lack of inspiration? If your hands refuse to comply, I can't quite help you, but if the lack of ideas bother you... Well, I can't speak as artist here, but whenever I get thought-blocked, and can't focus on the matters ahead, I go for an hour-long walk through the city. No destination, just going wherever it takes me. It helps me let lose of my current thought occupation and let my mind drift into the city-flow. It's one of the advantages of living in ones capital city, I guess.

But sometimes it can come as easy as to listen some music for me. Say, skyclad for example.

I don't know if any of my methods work for you, but I am certain if you find something else that lets your mind go, you will soon be back on track.

I know what this is like. This happens mostly when nothings going on, and i have time to draw.

Well, it's better to keep producing a lot of things that you don't quite like than nothing, at least you won't let the habit and skill out of your fingers~ the more you do the more you improve, even if the quality is worse than what you are usually used to, the trend is always going up, just imagine your skill level like those graphs on the carbon dioxide levels, always going up but with periodic dips and rises!

I'm currently in an artistic ascesis. Just keep on truckin'...

An artistic ascesis, haven't heard that particular couple of words (in that order and all) for a long while, read them in something by Tommaso Palamidessi, I think it actually was the title of the work! Wouldn't help you much though.
I guess you could draw cubes and spheres lit from different angles reflecting on one another if you really can't come up with anything~ anything to not stay stagnant.

It's not that I don't have ideas, it's just that executing them with any kind of quality is kinda difficult right now. I'll just have to push through.

Well, exactly, you can't draw boxes badly unless you really try! That way you do something, and you can't really call it good or bad. A little like me and canons.
Don't worry, I'm sure you will here's to a quick recovery