I am 16 yrs old. 2 year ago suddenly one day i hear a popping sound in my left knee. But i did not care about it.Next the sound is growing louder . Then i consulted with a doctor. He advised me to do the mri. And as a result there is found that myANTERIOR CRUCIATE LIGAMENT OF LEFT KNEE HAS TORN PARTIALLY AT ITS TIBIAL ATTACHMENT. My doctor gave me vitamin d3 injection and calcium and 3 week bed rest. But still now my knee is not stable. And i amfeeling pain.in my knee joint. Now what should i do