The conditions to consider for your pain are;
1) Achilles tendinitis
2) Retrocalcaneal bursitis
3) Plantar fasciitis
4) Calcaneal periostitis
5) Calcaneal spurs
A combination of above is also a possibility.
The treatment is almost same for all these conditions with the minor variations. Following may help you;
1) Moist heat or ice compresses; whatever suits you
2) Anti-inflammatory analgesics like Ibuprofen
3) Local analgesic ointment /spray
4) Physical therapy
5) Deep electrotherapy like iontophoresis, phonophoresis, short wave diathermy, electrical stimulation etc.
6) Consideration of steroid shot
7) Shock wave therapy
8) Custom-fabricated inserts
There is a new therapy called as autologous blood injection in which your own blood is injected at the pain site, is said to be quite effective. Shock wave therapy is available in sport medicine clinics or physical therapy clinics. This too is suppose to help in the resistant cases.
It is pleasure and privilege assisting you.