I had the same problem years ago. It got worse over time until finally I needed to have surgery to remove the permanently-damaged tendon, replace it with part of a tendon from another part of my foot, and move the heel bone 1/4 inch to relieve pressure on the tendon. It was a painful experience that took a long time to heal.
Get rid of all the shoes that provide no support. Address the overpronation problem. Wear whatever shoes you need to wear at work, regardless of how they look with dresses and skirts. Just tell people it is necessary to heal the tendonitis.
Good luck.
- Gray 2010 carbon WSD road bike, Rivet Independence saddle
- Red hardtail 26" aluminum mountain bike, Bontrager Evoke WSD saddle
- Royal blue 2018 aluminum gravel bike, Rivet Pearl saddle
Gone but not forgotten:
- Silver 2003 aluminum road bike
- Two awesome worn out Juliana saddles