hi.
my first thoughts phil are that there might be something other than a ligament tear going on. you sound very sensible with regard rest and progression back to exercise. four months from initial injury and your still having symptoms on running despite rest from aggravating activities would make me a bit suspicious.
i would recommend at the very least having your knee assessed by someone competent. at this stage a proper diagnosis is key to how this problem progresses. look for a physiotherapist experienced in sports injuries/manual therapy and get it sussed out. sooner rather than later!