Of course the first : thing one thinks of is trauma.... did you injure it in some way? Other thoughts would be a Baker's cyst or fluid collection behind the knee or, less likely, a blood clot. The only way to know is to be evaluated, perhaps considering an ultrasound exam. See your Doctor. Good wishes:)
Answered 11/30/2016
867 views
2 doctors weighed in across 2 answers
5 doctors weighed in across 2 answers
90,000 U.S. doctors in 147 specialties are here to answer your questions or offer you advice, prescriptions, and more.
Ask your question