It sounds like you have so much swelling that it made the splint too tight and this can cause damage to your circulation and nerves in your leg. I suggest you go back to the ER now and leg them know, and request more pain medications.
When you get home, make sure you elevate your leg higher than the level of your heart to keep the swelling down (at all times except to go to the bathroom). Also apply ice packs for 20 min. at time 6x/day for the next several days. In between, wiggle your toes every hour to help with circulation.
If you develop more swelling, loss of sensation to the foot or leg, go back to the ER again.
I meant i dislocated my fibia off of my tibia.