<s>[INST] hi, I fell down the stairs 2 weeks ago and hurt my leg, the way I fell I landed on my shin, there was a bruise but now that its gone there's a small hard lump under the skin about the size of a pea. its sore to touch, and I still feel pain while I'm walking. do you know what this could be ? [/INST] hi I understand your situationyou got hard painful lump after traumaDiagnosis:its most probably a sub-periosteal hematoma formation due to direct trauma to your shin then gradually became harden due to fibroses.it will be painful due to movement and touchingTreatment:you can let it and apply gentle pressure over it with taking topical or oral painkillersif no benefit you can excised by surgery by specialist. </s>