Hi DD,
after being on danceforum for a while, found out about salsaforums.. saw your post... and hád to answer, so i registered...
please, never ever again put on shoes with rubber soles when you go dancing! as you've noticed, you'll ruin your knee. a friend of mine hasn't been able to dance for 1 year, after continuing dancing with this kneeproblem. from time to time, when she's been dancing on a concrete floor for example, the injury reapears...
salsadancing with all its turns, quick changes in direction etc, puts a lot of twisting strain on your joints (knees and ankles). So it's very important to wear shoes with soles that allow you to rotate on the floor, without too much friction (so, best are leather or suede soles)
i'd say go to your GP, give your knees rest for a coupla days, and then try dancing again, this time with the right shoes...
sometimes a kneeband may help a bit to keep your kneecap in place, and ease the pressure on the joint.
don't use the ibuprofen, coz the pain is a means of your body to say: hold it there, your not treating me right, something is going wrong.
If you use the ibuprofen to not feel the pain, you'll keep damaging your body, and it may become chronic.
good luck