I have had plantar fasciitis for six months now and have worn the night splints and a walking boot and had custom orthotics made but still have it.  My doctor wants me to see a physical therapist.  What can they do for me and is this necessary?

A physical therapist will at your overall alignment (joint structure), how you move, and will tease out any muscle imbalances that might be contributing to your ongoing plantar fasciitis.  They also can perform adjustments if need be, fabricate orthotics, and use manual therapy as well as some modalities to help you get rid of the plantar fasciitis and hopefully keep it away for good.  Especially since you were in a walking boot for a while, follow up with some ankle strengthening is indicated.