I Injured My Shin Bone (no Fracture) While Ziplining. I

I injured my shin bone (no fracture) while ziplining. I hit my shin on a wooden platform going approximately 15 - 20mph. I now have what the doctors are calling a large hematoma on my shin with bruising all around my lower leg and foot. I was given orders for an MRI but am wondering if it is worth the time & money to get it done, or if I just need to give it more time? The injury occurred 2 & 1/2 weeks ago.