Cramping and near fainting

I was finishing up a shower when I started having some mild cramping, followed with some waves of nausea. I thought I might need to go to the bathroom so I sit down and go and then I get hit with a wave of feeling overheated, dizzy/lightheaded so I lay down on the bathroom floor. I'm still cramping, but after a few minutes I no longer feel like passing out. I had an episode where I felt like passing out last week and now it's happened again with cramping. I'm worried! The heck is going on?