In conjunction to the shots, you may consider physical therapy and/or wearing a night splint.
The night splint will help you maintain a continuous, gentle stretch of the plantar fascia. I will guess that the pain is worse with the first few steps in the morning and after you've been sitting for a while..???
Here's a quote from a google search:
Night splints, which are removable braces, allow passive stretching of the calf and plantar fascia during sleep, and minimize stress on the inflamed area. According to several studies, approximately 80% of patients improved after wearing a night splint. It may be especially useful in patients who have had symptoms for more than a year. (http://healthlink.mcw.edu/article/987116429.html)
Of course, though, if you *do* decide to try a nightsplint, please let me know and consider one of mine:
https://secure.roycemedical.com/royce_medical.html
(If you get routed to 'Ossur' click on the button to 'continue to Royce Medical')
-Aude.