When you twist or sprain an ankle, it can feel totally healed, and then bother you after hiking for a little bit. What should you do in this situation? You let it heal! Bracing the ankle won't help much as it won't let it strengthen back up from your injury, making you rely on the brace whenever you push yourself.
Your body needs time to heal. So first, go see a doctor! Just be safe and have them check it out, especially if you're having trouble walking on it. It's possible there is a tear, infection or bigger problem if you can't walk on it easily, so it's best to check it out right away.
If you can afford physical therapy or your insurance covers it, I highly recommend it, especially for grade 2 or 3 sprains when the ligaments are involved!
Even if you don't go to a doctor, make sure that you ice the ankle for 2 - 3 days using standard icing practice. Don't put heat on it in the first 24 hours, but after that, alternate between heat and ice (15 to 20 minutes each) to improve blood flow to the area and enhancing recovery.
Otherwise if you can walk on it normally, I would recommend doing some ankle mobility and strengthening exercises that would probably help much more than a brace! After the first couple of days, your priorities are (in order) range of motion, stabilizer strength, and weight bearing. Because of my specific injury in the past, I found great improvement when I started wearing night splints to keep the back of my ankle from healing short. I still wear them. When I wake up in the morning, I spend a little while wiggling the foot around to limber up, then hop on the wobble board and do 20 circuits in each direction. That loosens things up for the day. Wobble boards are great for working with ankles! Check the video above to see how to use one.
Try these, and then give it time to heal, and slowly get more active as it heals. But, you have to do some activity to help it heal correctly: if you do nothing, nothing will get better in the right way!