How To Determine A Broken Ankle?

Today I twisted my ankle and went to the E.R. they took xrays and the P.A. said that he thinks I just have a sprained ankle. Is it possible to mis-diagnose a sprained as my grandmother, who is a nurse, and i both think I may have broken my ankle. I am unable to bear any weight, it is constantly in pain, and is discolored and swollen. Is it possible it is a break. I will be going to my P.C.P. tomorrow to have him give it his opinion because my grandmother had the same problem with the same E.R. 20 years ago and it turns out her foot was broken in 4 places.