A swelling that is prominent at the back of your knee could be a Baker's cyst or popliteal cyst. Baker's cyst or popliteal cyst might disappear sometimes on its own. Best Home Treatment for Bakers Cyst or Popliteal Cyst Would be Following the R.I.C.E. principles.
This home made ice pack can be in your freezer all ready to go for bumps and necks and hardly costs anything. One part rubbing alcohol to three parts water. Gets really cold but never hardens. Just like a real cold pack! :)