what's wrong with my ankle?!

I slipped on a night out about two weeks ago and think I sprained my ankle. Couldn't walk on it at first but could walk again without any pain within a day.

However, a week ago it started hurting again despite the fact that I haven't slipped or done anything to it since. It's a little bit swollen and it hurts during and after i've been walking and when I apply pressure to the inside of my ankle.

It's not immensely painful but it's been a week and it's still hurting. I'm just confused to how it stops hurting a day after injuring it but then starts again a week later.

Thanks for any information/advice you might have.