last week while my 3 1/2 year old toddler in Taekwondo class, this psycho kid took taekwondo punching pad and hit my son s chest using its edges. The instructor and i heard this SCARY LOUD HITTING SOUND, we turn around and heard my son kept saying ouch holding his left chest for a few minutes. He was in pain. When I lifted his shirt, we can see the imprints of the edges of the pad on him. He appeared to be OK afterwards and since then. But from time to time, I would feel his left ribs for signs of problems. It is a hit and miss. Sometimes he would say ouch and sometimes he feels no pain. I am not sure what to do right now. there are no bruises nor swelling .