Neck Injury

I have been pushing myself more then last week (with more practice than usual this week, back-to-back) and it seems that the extra swimming resulted in a minor neck injury. Though my neck didn't hurt at all in the last saturday+sunday practices, when I was doing some informal stretching on Monday I began feeling a sharp pain when I turn my neck far to the left or right. It seems to be only one muscle (probably), but for each direction it is pulled a different way so the pain is slightly different. I originally thought it was just a coincidence, but when I returned to swimming on Tuesday I noticed it began hurting when I did my freestyle breathing on the right side. Although I had worked on this in the past (with a video that many people were nice to give comments on), I think I have either fallen back to breathing by only turning my neck (as opposed to whole body), or maybe never improved my posture as much as I thought. Either way, I need to take it easy for awhile to let it heal, but I wanted to see if anyone had any suggestions or had this sort of injury before. Today I am planning taking it easy, with a mostly kick-only session which doesn't seem to aggravate my neck at all (because it doesn't turn), and I am considering continuing breastroke because that only moves my neck up and down (with no horizontal movement) so it is should be safe. However I really want to fix the underlying problem this time, I think my need to get oxygen is still stronger than my need to have a proper posture, so its very hard for me to maintain freestyle breathing where I don't turn the neck at all. I am generally trying to do more body rotation and make sure my shoulders are nearly vertical on each side rotation, but if anyone knows any drills that might help with this please let me know. I was even considering trying to swim with some sort of neck brace that limits the motion of my neck - thereby forcing me to turn my body to breathe - but that seems a little crazy.