What Causes Bruising From The Mid Of Calf Muscle To The Achilles Tendon?

I am a female, 26 yrs old, 5' 3", and no serious medical history. It has been close to 2 years that I experience trauma to my calf from a solid wooden pallet that left a bruise from the middle of the calf down towards the achilles tendon. The color of my skin is still "black and blue" and I wonder if I should be concern. When pressure is applied towards the achilles tendon it still hurts but nothing unbearable. Is this something serious that can cause an infection or a disease?