I know how you feel, i go through stages, it ive been playing so long now i can almost predict when its going to happen, seems like after i practice alot i get bored or lathargic, i cool down for a bit and think to myself **** the endless regimated practice and just noodle or not even play it for awhile. and i find my body seems to come back up and all of a sudden im motivated to play and a feel much better than i did, even tho i just noodles.
i think its just the fact that too much of one thing leaves you subconsiously unmotivated, its like looking at a minute hand on a clock, very focused but very boring.
take a break and dont feel you have to get better just play for the sake of playing, and by the time you look back at the clock it will have moved along much further
^^^^ that was a metaphor by the way.
so i guess my point is chill relax, play what you feel and dont worry about anything else and then your brain will suddenly get motivated to play some hardcore rock!
my 2c
dan