Hit my upper leg on edge of table very hard a month ago. Had a huge bruise and pain but it's gone. Now I touch & feel a hard lump under skin. Hematoma?

WeAllTakeOurLumps. Yes, it could be what remains of a hematoma under the skin. That lump could be there for a few months but the body absorbs most or all of it. Nothing dangerous. Sometimes some scar remains forever but shouldn't be a problem unless you can see it and it bothers you. But, if it starts growing or begins to hurt or the skin discolors, get it checked out.