Heat actually isn't good for sprains. Heat expands the muscles, which you don't want. Continue to ice it if it hurts, but what you're really trying to fight is inflammation. The three best ways to do that (without having to take a pill) is icing, wrapping and eating.
Get an Ace bandage or something like that and keep it on your wrist as much as you can. Not too tight to cut off circulation, but tight enough to give it support and keep swelling down. It's a bit far away since your injury, but that kind of preventative care still helps. (Trust me, I wrecked my three weeks ago).
A big thing that people barely think of is their diet to prevent inflammation. There are some core foods you can eat to keep swelling down all over your body. I recently came across this slideshow this health site put together. It's pretty good. Check it out: http://www.healthline.com/corporate/rheumatoid-arthritis/treating-rheumatoid-arthritis.html
So, keep icing, stop heating, start wrapping and eat healthier and your wrist will be better before you know it.