My rabbit is around 3 years old and he isn't using his front left leg and I have no idea why. He will walk on it ever once in a while so he won't fall over but other than that, he won't walk on it. he lays down, sits, and sleeps protecting it unlike his other front leg. Please help with info on what's wrong or how much a doctor's visit would cost for an examination and or a surgery for him. He is the gray, white rabbit.