Dude, I've jacked up both my ankles more times than I can remember! There's a few things you can do to prevent swelling:
1. Ice massage (take a little paper cup, fill it with water, freeze it, take it out and tear off the bottom of the cup and massage the sore area for 15 min at a time). Do it two or three times a day.
2. Elevate, while you massage, while you sleep, while you watch TV, anytime you can. The higher the better. I usually do this when I go to bed, and just stack a couple of pillows under my foot.
3. Compression during exercise or walking. They make a compression sock you can get at the grocery store, or just wrap it.
Lastly, on the workout stuff. It's best to let it get better for a few days before hitting the gym hard. But if you can't wait (like me) try to do exercises that limit the stress on the lateral (outside) portion of the ankle. And if pointing your toes up hurts, stay away from movements that aggravate that. I would definitely lay off the heavy impact and reactive work for a few days. So, here's some substitutions that might work:
BB Squat = Box Squats on the smith machine (concentrate on driving with the heels, and the smith machine will limit required stabilization)
Standing Calf Raises = Calf Raises on leg press (that way you can't go to deep, but I would probably take it easy on these)
Leg extensions, leg curls, GHR, deadlift, SLDL, RDL, Good Mornings, should all be ok. Let your body be your guide.
Golden Rule for the next week: If it hurts, don't do it! Now is not the time to push through the pain. Should be better in a week.