unfortunately that is one of those injuries that tend to be long term. The problem is that even though you rest it from running, you cannot completely rest it because you're walking on it and therefore putting some stress on it every day.
The best advice I can give is find a Sports physio with a very good reputation and follow their treatment plan... but it will take time I'm afraid
I suffered this injury for some 18months and there is only one real cure......you won't like it....REST! I was fortunate in that I got a new job which entails me cycling to and from work each day so had the chance to build up and keep my aerobic fitness. I went to a specialist on the NHS and she told me to be sensible, if I felt like a run...run a little...it's a slow injury but with time it will ease. I got some good insoles on the NHS and put in all my shoes both sports and work and with a little patience....and a little cycling....and then a little running I got back to running. Did the Bath Half Marathon 2 weeks ago with no real bad effect although I have to be careful not to overdo and risk the injury returning. So in short substitute running for a while, introduce a little cross training.....and some day in the not too distance future you should be back on your running feet.....but don't rush it!! and don't give up hope