Last Few Days My Right Ankle Sort Of Felt Like

Last few days my right ankle sort of felt like a sprain, but I don't remember doing anything to make it hurt. Then last night when I was falling asleep I had a severe cramp in that foot and one of my toes was bent for about 5-10 minutes. After rubbing it for a while the cramp went away. I just looked at my foot now and it looks like a knot just below the ankle bone and it is sore, but not terribly. Is this a sprained ankle? And how should I treat it? Thank you !!