Ankle pain on outer side of right. I was at MORP last night and when I was dancing I rolled sideways on it. Mild bruising and swelling. Pain when walk.

Be examined. If you have stopped growing, this is most likely a ligamentous injury. This is managed with elevation, cold packs every 2 hours, limited activity and NSAIDs. See your doctor if you are not improving or there is any concern for a fracture. All the best.
Sprain. Sounds like a common ankle sprain. Ice it for 20 minutes out of each hour. Wear a support so it doesn't happen again, until the strength returns.