2-3 days ago I came home from a long walk and it felt like my ankle was bruised. I looked at it and there was a huge bump on both sides of my left ankle. It was red and swollen but it wasn't sore unless I touched it. My mum said it wasn't a mosquito bite or any other insect as it should be itchy, not sore. I had trouble sleeping last night, as the 2 bumps on my ankle got really bigger, and I can't move my foot as the skin feels stretched and sore. I now find it harder to walk than the previous day and it's really itchy. 

My mum suggested I might have sprained my ankle, but for some reason I can still walk on it (even though it's painful), and I'm pretty sure if you sprain your ankle you can't walk on it at all?

Also, I bought new shoes 2-3 days ago and when I started wearing them that's when my ankles started to get sore. Could this be the problem?