I Have A Sharp, Stabbing Pain In My Left Outside

I have a sharp, stabbing pain in my left outside ankle. I had a severe sprain 10 years ago, and sometimes my ankle acts up, but it has never hurt like this. I cannot put any weight on it. They did an x-ray and found nothing. It's in a boot now, so I can at least stand and walk some. Without it, I cannot stand at all. The pain level is definitely a 10.