Longer recovery time after long runs

Hi! My long runs recently started getting longer as part of my half marathon training plan and i'm noticing pain in my knees after them that can last 3-4 days (pretty much can't run on them). I have started more intentionally incorporating strength training to help combat this but I have an 11 mile long run next week that i'm worried about. What else can I do to help cut down on the recovery time? Half Marathon is at the end of March and I want to make sure i'm in good shape!