What Causes Pain In The Knees While Bending?

I am pretty active and 2 days ago I noticed some knee pain. That morning I went to the gym and did squats & lunges without issue and in the afternoon I played beach volleyball. Now it pops when bending past 90 degrees. Ther is some pain when banding as well. I did not notice any swelling and have no problem when walking. My calf is also tight and heal aches. Should I continue to rest, ice and wait & see or is a more proactive course of action required.