2 year old keeps saying her foot is soar underneath but there are no physical signs of injury or a splint or rash?

Hard to interpret: A 2 year old just starting to use language may not be easy to interpret. Sore may mean something different to them than you but it is worth monitoring. A cool compress applied to the area might be helpful as this could just be a bone bruise or other trauma you would never be able to see. It would also give them the reinforcement that you care.