Extreme Leg Cramps!!!

Woke up this morning to a leg cramp in my right calf muscle! !! I started panicking as I tried to pull my toes/foot back to stop it, and then the top of my left ankle begins to cramp along the bend of my leg and foot. Mind you this is while my right calf muscle is in a ball mid muscle! I'm trying to sit up from the couch while both legs are freaking out, so I call for my husband to quickly bring this leg cramp cream I found at Sprouts (no idea if it works yet or not). Well the leg cramp cream is nowhere to be found. So I asked my him to quickly get me hot washcloths since I know these can work too. He's running back and forth between the couch and the kitchen sink reheating the towels....poor guy, nothing like a 5am wake up! Good gravy that hurt. The right leg calf muscle relaxed first, but my left leg ankle bend would not relent. Just trying to relax my leg with towels on it did eventually relax that muscle and as I'm typing I haven't moved either leg hoping my body will stop this cycle! I thought I beat this by taking Magnesium which believe me has prevented this until now. (35 weeks today) Due date is August 30th. My husband is about to leave for his new job training by this weekend and I'm going to be alone with our 4 beautiful daughters. Dear Jesus, please have mercy on me! Anyone know other things to do to prevent this from happening?