I Have What Seems Like A Void Or An Air

I have what seems like a void or an air bubble under the skin next to my shin. When i pull my toes towards me it creates a hole. When i extend my foot it creates a bump. Its about the size of a dime. I did break my tibia over 5 years ago, but it was about 4 inches lower very close to the ankle. Its not painful, just weird. Should i be concerned?