Workouts with bad knees?


Hi all! I've been doing FB workouts since August and I am loving it! I've run into a bit of a snag though... I've recently been pairing it with running and somehow screwed up my knee and ankle (opposite legs of course). I'm assuming it was workout related but I'm not sure how it happened. Anyways, even using stairs a few times in a row aggravates it so I have been off my game (I'm missing my 30 min. HIIT & strength workouts!). Any ideas for staying in shape (I'm in a wedding in a month) without aggravating sore lower body joints? Thanks guys!