Hi. I'm sorry this happened to you. Biome people don't know their own strength!
There are no doctors on this forum. We are all chronic pain patients that share information and give support to each other and:or others who find themselves in pain.
This has been going on with you for quite some time now. Have you told your parents or seen a doctor about it yet? It could be several things. We have bones, muscles, joints, tendons, ligaments, etc. and it could involve any one of, or a combination of, those structures.
I'm sure it must be hindering you a bit and I'm sure you'd like to get back to your regular activities without being bothered by this pain. Tell one of your parents so they can get you in to see a doctor so you can finish up healing.
He could have bruised some of your bones, and that does hurt. Try soaking in a warm tub with Epsom salt, this helps to relax the muscles.
If it continues, I would suggest letting your folks know and seeing a doctor or even a chiropractor, this person could very well have dislocated some of your vertebrae.
Chest wall, intercostal and rib injury take about 6 weeks to settle because the chest is always moving. Glad to hear you are getting there.