Sprained ankle 11 months ago but ankle is still weak and stiff. could it be causing my ball of foot pain? perhaps plantar fasciitis? achilles t?

Sprain or fracture: Was it x-rayed? If it is not a missed fracture or widened mortise, your inactivity could be a cause. Failure to dorsiflex your foot fully will cause metatarsalgia-forefoot pain. Plantar fasciitis although it is a really different problem is about the underside of the heel and is actually a bursa. If it was neg/x-ray start runner's stretches and get the ankle loose.

Head to toe..: Until the elements of the previous ankle sprain are dealt with expect more of the same. The stiffness and weakness have, in a sense, effected the the mechanics of the entire limb. This is known as compensation. If not addressed, your knee, hip and lower back stability are at risk. Consult with a physiatrist, podiatrist rehab specialist or an orthopedic surgeon for further details.