Rigid orthotics can sometimes cause stress fractures up the fibula so if your problem just keeps getting worse the get a bone scan or X ray to exclude this.

Physio should continue to mobilise the proximal tibiofibula joint and also your subtalar joint. These joints work in together as a shock absorbing mechanism when you are running. Strangely enough sometimes the ankle joint can be causing this kind of pain so you should includ some stretches for this as well.

You may be OK with more flexible orthotics.

Dont forget to keep up with any stretches and strengthening for your Wikipedia reference-linkSIJ and piriformis.

Good luck