Knee injury and Flexibilty

I was finally improving my flexibility, getting close to full butterfly when I popped ligaments in my knee from a heel hook about 6 weeks ago. I'm back to training but my knee still feels stiff and weak, especially on lateral movements. (ie pulling your foot to your face, RG type movements.) has anybody had a similar injury and been able to continue to stretch? As of right now when ever I get into butterfly I can't push because of the pain (in my knee, not my groin). Any advice would be appreciated