As a sports physical therapist, I will recommend you to read this article first. You can download the full article with a click away. However, I will sum up the best available scientific evidence on how to treat plantar fasciitis.
Basically, you want to do these things (straight from the literature):
Dexamethasone 0.4% or acetic acid 5% delivered via iontophoresis
can be used to provide short-term (2 to 4 weeks) pain relief and improved
Prefabricated or custom foot orthoses can be used to provide shortterm
(3 months) reduction in pain and improvement in function.
There appear to be no differences in the amount of pain reduction
or improvement in function created by custom foot orthoses in
comparison to prefabricated orthoses. There is currently no evidence
to support the use of prefabricated or custom foot orthoses for longterm
(1 year) pain management or function improvement.
Night splints should be considered as an intervention for patients
with symptoms greater than 6 months in duration. The desired
length of time for wearing the night splint is 1 to 3 months. The type
of night splint used (ie, posterior, anterior, sock-type) does not appear
to affect the outcome.
Go and talk to a physical therapist who is either a board certified in Sports Physical Therapy or Orthopedic Physical Therapy to get indepth information about your problem. By the way, your physical therapist should be able to recommend you on what exercises or activities you can and cannot do in the meantime.
Hope this helps and good luck!