I used to have similar problems with similar grips. Are you gloves gel gloves?
If today is the first day you have ridden without gloves and the first day you have had cramp then I suspect you have the answer...
If they are gel gloves , then the gap between the gel pads on the palm of the hands close to the wrists has been protecting your nerves running through there and without the gloves is why you are having problems with those grips.
I always change the grips on my mtbs' over to the ergon type. Something like this link
http://www.wiggle.co.uk/ergon-gp1-h...m_medium=base&utm_campaign=uk&kpid=5360314960 works wonders for me (and I have had 11 ops on my left wrist, numerous trapped nerve issues and carpal tunnel, bones removed, bones shortened and so on, etc...) with these grips, once in the correct position, the problems usually vanish to an odd tingle every now and again - but I could be jumping to conclusions if the gloves are not padded ones. Some people are fine with original grips - I'm not one of them! (think of them as an investment to transfer from bike to bike if and when you upgrade - they last and last...)