Hi, I Recently Injured My Knee, Where A Friend Pulled

Hi, i recently injured my knee, where a friend pulled my ankle to the right causing my knee to pull sideways outwards to the left, until the point i felt a clear pop. I had a xray which showed no breaks or fractures. I can now walk on the leg after 5 days however it hurts to go up and down stairs, and doesnt feel right. There is also slight lump still on the inside of the knee just below it. There seems to be a constant dull pain. Any help would be appreciated, thanks.