My 7 year old son feel onto an exercise (smaller) trampoline while trying to do a flip. He landed on the side of the trampoline square in the middle of his back. There was immediate redness and bruising. He cried pretty hard. It did not knock the wind out of him so to speak but he was complaining of not feeling well at bed time. His back was sore after the fall and it hurt to move around too much however he is able to stand, walk, bend over to touch his toes etc... no dizziness or tingles or numbness in any extremities. This was 2 hours ago. He s asleep now and snoring. Should I be concerned of internal injury?