Hi Dr. Rynne, My Son Ryan That Is 19 Years

Hi Dr. Rynne, My son Ryan that is 19 years old just noticed a significant knot behind his right ear. Later he found 2 more knots on his head located on the right side of his head towards the back. Ryan was involved in a car accident about a month ago. These knots were just noticed this week. They are tender to the touch. Do you feel it is related to the accident or something else. The knots do not have a head to them as a boil would. They only appear as a knot under the skin with no discoloration. Thank you.