The problem by now is that there is fibrosis/calcification happening within the plantar fascia this makes it stiff. You will need to break this down before you feel any big relief if you want exercise for this check out utube or this site Plantar Fasciitis Treatment UK | Exercises | Plantar Fascia Strain. However with your previous history and present 4 months duration and trying orthotics I would seek Shock wave Therapy or ESWT. It works normally within 1 month and only 3 treatments should be needed. Check out this site for more information. London Shock Wave Therapy Clinic - shock wave treatment in london
good luck!