5+ yrs ago I had a bad biking accident and blew off the elbow pain but now have a strange hard lump on it and tenderness, should I be worried?

Get it checked... Any painful lump or mass should be evaluated. It may be related to your previous trauma or possibly be in the same area but have nothing to do with it. It can be benign and harmless or potentially be very serious. I highly recommend thorough evaluation by a physician.
Yes. Could be a bone spur, loose body, or scar tissue. Get it checked by an orthopedic specialist.