Is my ankle broken, or sprained or what?

I skateboard at skateboard parks all the time, and i went to ollie up a very steep ramp, well somehow i fell backwards and my foot slammed up against the ramp, i sorta fell on and like stubbed my foot up against the ramp like you would stub your toe. And i got up and it hurt really bad, i fought through the pain and kept skateboarding. Well its the day after and i cant walk very well and it hurts so bad! Whenever i step down it makes a cracking noise.My mom thinks i popped it out of place and its been thumping all day long,i dont know if i should get it x-rayed. Maybe its broken or sprained? Its getting annoying that it keeps popping.