I walk 2 miles every night and my left ankle to mid shin really aches. what is this and how can i make it stop?

Likely shin splints: This kind of exercise causes lots of stress on your bones. If your weight is in a good range, i would ask your family doctor to consider x-ray to look for stress lines of increased calcium. If they are there you mild want to alternate swimming with your walking to decrease this stress.

Shin splints: Shin splints is the first thing that comes to mind. Proper stretching before and after exercising is helpful as well as icing the sore areas after a workout. If this is not helpful, i would see a doc and be evaluated. There is a more serious condition called a compartment syndrome that may be the cause.

Shin Splints: Best to support arch with orthotic. Ice after walking helps. Try to walk on a flat surface avoid hills.