I've been practicing pretty rigidly as far as routine goes for the passed week or so. Tonight as I was practicing, my picking hand tensed up real bad and I am unable to keep and even rythm no matter how much I've stretched or tried to relax. Is there a such thing as overuse? Because if this isn't a normal thing with guitarists I should probably visit a hospital. If it is normal, what should I do to fix the problem? Just back off of guitar for a few days?