Oh that poor baby.....I hope he gets to feeling better soon. Yes, Tylenol or Motrin is all we can give them at that age. My son is 20 mos and that's all my doc advises too. Motrin will be better as it is an anti-inflammatory med. Tylenol just relieves a little pain.
Ice would be great on his ankle, but getting him to sit still is another story. lol Elevating his leg will help a lot and will relieve some pressure. When our legs are down, you can feel the throbbing of the blood flow, but when elevated, it relieves that throbbing. An Ace Bandage would help brace his ankle too.
Ankles are real sensitive. Have you ever had a sprained ankle? I have had about two or three. One time I had sprained my ankle so badly that my foot started to bruise up. It was awful. And once you sprain your ankle, the ankle is kind of weakened and is more prone to being sprained again if it isn't healed up all the way.
I hope your little one feels better soon. My kids haven't had a sprain yet, but if they ever did, I know I would go nuts, pulling my hair out, wanting to just wave a magic wand to me the pain go away.
Oh, and two, since he hurt his foot, he will be reluctant to putting pressure on it for fear that he will hurt it again. It will take some time. Hope this helps.