^^ Yes. Bike fit is a big deal. Improper fit can be really hard on lots of your joints, especially the knees. Make sure your saddle is in the right spot (front-to-back), and your bars are high enough/spaced correctly (also front-to-back -- stem length).
Take a rest. Ride easier, and slightly less than you normally would, for a few days. Don't completely stop, since a little all the time is better than lots & then none.
Gear down slightly, and use your brake.

Take care of those knees; you need them!