Re: Swollen groin lymph node caused by sever sprained ankle?
The vast majority of swollen lymph nodes are not cancer. Most people have a swollen lymph node many times in their lives, in fact.
It could be an infection somewhere in your body. It could be irritated (maybe due to walking funny from the ankle sprain?), it could have happened for no reason anyone will ever know.
Don't poke at it too much, that'll keep it swollen. Just keep an eye on it. If it goes down within a few weeks, no need to worry.