I also have some of the boots designed for this. They are just for sleeping and sitting around the house. They keep the ankle in a 90 degree angle, so the foot isn't straightening. This keeps a continuous light stretch that helps a lot. There are lots of different kinds on the internet or you can get them at a medical supply store or through your doctor. Price ranges from $20 each up to around $80 each.
Taping the foot is also helpful - ask your podiatrist how, or PM me. The right taping pulls up your arch and stabilizes the foot. Arch support is critical - When your arches are flat, your foot loses springiness, and that contributes to heel pain.
Good shoes are essential. We are fortunate to have a family owned shoe store that has been in business close to 100 years, where they really know how to fit you and only carry high quality shoes - athletic, orthopedic, whatever. When I walk in and look at something the owner immediately knows if it will work for me or not! He usually picks for me, and he's always right. They also add/subtract inserts and modify as needed.
Anyway, I've had great luck with SAS, Aetrex, InStride, and Etonic. Nikes might be ok too, though you may need to add gel or other pads.
Regarding injections, I had one in my knee for something else - it only lasted a week or two - but the orthopedist said he would only do them three times a year. I guess the cortisone eventually goes through your body and is strong stuff. For a day or two after my injection my face was flushed and I felt kind of ill......perhaps it didn't stay in the knee and that's why it didn't last as long?