knee pain

nataliecarter28

I'm on day 17 of the jillian micheals 30DS and my knees are killing me. Its a lot of squats and lunges, which I do the best I can, (and I always watch my form) but it is starting to really hurt my knees and ankles. does anyone else have that problem? are there any good excersizes or stretches I should be doing to strengthen those joints or ligaments or whatever it is causing this pain?