Knee injury. And what should be done.

I suffered a road accident on 1st march and had a knee injury. MRI showed tibial avulsion tear of ACL and also MCL tear. I had my arthroscopic surgery on 25th march. Doctor repaired my ACL by binding it together and left MCL for self healing. I was advised to not bend my knee for 3 weeks and after 3 weeks bend it slightly by laying head downwards for another 3 weeks. Now 4 weeks after arthroscopy I can't bend my knee beyond 20-30 degree and if i try to increase flexion it won't happen and knee would pain. Swelling is  normal too. I want to know if it is normal to not be able to bend my knee or it is something to be looked upon immediately. Will i have to go for another surgery or flexion will come. Right now my knee can't be flexed. And how long it will take and what should be done.