How Can A Swollen Bone Knot On The Elbow Be Treated?

My daughter is 4 years old. Yesterday she developed a lump, or knot, just above funny bone area on left arm under the skin. There is no redness or bruising, but the area also looks swollen. She has also said the arm pit area hurts if touched. And she is NOT running a fever. She has not fallen, been pinched or had shots recently. We recently lost insurance on her and do not have alot of money, should I be going to ER or visiting DR anyway?