Running downhill is challenging. For me the biggest challenge is to learn that I can trust my body and relax even on difficult surfaces and steep slopes.
Fear of pain can be a self-fulfilling prophecy. If you fear pain then you´ll probably tense up and eventually get pain. This is difficult to overcome. The mind and the body need to be relaxed at the same time. I believe that this cannot be achieved by working on the form only.
I´ve learned that I can handle difficult down-hill running best when I focus on self-confidence ("I can trust myself..."), a relaxed body-feel and if possible even fun. Sometimes it feels like skiing downhill, then I know I´ve found the right form. But I can´t tell you specifically how I get there when it happens (it doesn´t always happen).
What I know is that I play with what the arms do (keeping them high or low, using them for balance). I experiment with how much leaning back works well. To force myself into making very quick steps doesn´t work, this leads to making more mistakes (e.g. hitting rocks too hard). Beyond a certain incline it is too steep to just let go, but braking is still bad. By all means you need to remain relaxed, however steep and difficult it may be.
So my advice is: practice, trust yourself, make it feel easy and relaxed. Eventually you´ll find a way that works for you.
When I started to learn bf-running I hated such vague, esoteric tips like the one I´m giving here. (E.g. "relax, relax, relax", "experiment", "everyone has to find his own form"). Now I´m doing it myself
. I hope it helps.
P.S. Ashley, do you have reason to be worried about your feet (apart from the stress-fracture last year)? Are there any signs of running into a relapse? If so, you might need very different advice.