My Mum Is 76, She Was Walking Yesterday And Says

My mum is 76, she was walking yesterday and says she "went over" on her ankle. Whilst she didn't fall right over-she did stumble, now she says whilst her ankle doesn't hurt her calf does. Also, on the same leg she has a bruise/sore that has become infected and is on antibiotics. The sore is about the size of a 50p coin and appears to be healing. Is her calf hurting due to her trip or could it be the sore? Thank you.