My son who is 12 had his leg just above his ankle stepped on during a soccer game about 3 weeks ago . We took him to an urgent care center and the provider took a look and noted that it appeared to be just a sprain and did not think xrays were necessary. He stayed off of it for about 4-5 days then played soccer the following weekend. Still tender, but not bad enough to keep him off the field. He also completed in a cross country meet about 10 days after the sprain. There was not that much swelling and never really bruised, but now about 3 weeks later there is a knot forming right around the sight of the injury. He states that the area is tender to the touch, but is still able to walk / run with out too much discomfort. Any insight as to what this knot or lump may be?