you have achilles tendonitis. i would wear a 1/2 inch heel lift in both shoes to take the pressure off the achilles tendon. take anti-inflammatories if you can to help reduce the inflammation. a device called an Achimed can also help reduce the pressure from the achilles. when this all calms down, you will need to go to physical therapy to stretch this tendon. this condition starts when the calf/achilles is tight.
go see your podiatrist to initiate these treatments. physical therapy can also utilize ultrasounds and electrical stimulation to help.
but, go see a podiatrist to make sure there is no rupture or masses noted to this area.