Suggest Treatment For Plantar Fasciitis

HI I have been told I have Plantar Fasciitis I have never had any medical problems before, I am 50 nearly and my feet are so painful when I walk its really bad, when I sleep it is also bad, there is no specific time when the pain is better its on going. I have tried ice packs, baths,massages on my feet but still painful. I recently had injection for pain which did not work. My youngest son had Peripheral Neuritis when he was young and I am now wondering if I have the same. If you can advise me I would appreciate any help. Thankyou.