What is wrong with my ankle?

So, I have been doing some exercises to help my shin splints (I am in cross country) and one of them is walking on my toes. There was always a strange popping sound in my ankle while I was walking on my toes. Lately, it started to hurt a little when doing that. The other day, I was doing the same thing as every other day, and suddenly during one of the pops, there was a whole lot of pain like crazy. Something was also wrong with my Achilles tendon, but that is okay now, but the pain where the popping was is even worse. It is hard to walk, and I am always limping. An ankle brace doesn't really help. Suggestions?