Ouchieeeeee

Yesterday, I went for my 60 min walk, as usual, at lunch. Then after work I met my daughter at the gym. I worked on a machine, then did 10 minutes on the bike, and 20 minutes on the treadmill. So really not a whole heck of a lot. But, last night, I again had a hell of a painful entire leg cramp. Both legs from the ankle to the groin area. I have had this 2-3 times before in the last year. OMG, I thought, seriously thought I was going to die. The pain is excruciating, I cant walk them out or rub them out, the pain is so bad that I get ringing in my ears as if I am going to pass out. Is there any type of preventative measure to not get these. I have had cramps in my feet and calfs, yeah they hurt, but nothing like these. I do usually put a banana in my shakes every day.  Any advice would be appreciated.