Hard Lump On Leg, No Bruising Or Swelling. Worried

Hi, I seem to have a hard lump on the centrefront of my lower shin, just above my foot on my right leg. I m in the military and have spent years running around in boots and have never had this problem until now, just after I started preparations to deploy next year. After a few forced marches in the last 2 weeks, my shin has bruised and swollen up. However I haven t done any physical exercise for a week and there is no bruising or swelling but there still seems to be a lump on the front of my shin about an inch and a half up from my foot. This is just where the laced part of the boot would sit. It would be much appreciated if you could give some advice. I ve seen a doctor and he diagnosed tendonitis and gave me anti inflammatories last friday, however I m just a little worried about the lump that is still there.