Leg cramp during exersise

I was doing legs today i did squats i do higher reps now 6-10 reps iv been doing that for 2 weeks or so getting good results. i was doing squats good secsion after i went to leg press it was going ok during my 2 or 3 set i started getting a cramp on my weaker side i do leg press single leg to eliminate my strong leg taking over my right leg started cramp. I had to stop the quad workout and i did hamstrings and calves to finish i wanted to do leg extensions but i mised it.

Iv also started taking multi vitamin pills and drink plenty of water during my workout