I've got an imbalance somewhere on my right leg- I believe it be my quad. When I try to lift my leg straight back, my heel (and consequently, my whole leg) curves inwards. My question is, does this sound indicative of a quad weakness? Any feedback would be appreciated.
Sounds more like a tight hamstring or groin imbalance, pulling your leg to the inside. Try stretching hamstring and groin more, strengthen your gluteals (hip abductors)