In October My chicken started limping, her leg is not broken it looks like an infection, on the sole of her foot there seems to be an swolen lump she is about 5 or 6 and she has passed it on to one of my younger, healthier ones. What could it be and what can I do to help her?

A Vet is a good start, particularly if a second chicken has the same symptoms/signs. If you don't get this diagnosed and treated the entire flock is going to be affected.