Recently I've experienced a clicking noise on the drive side up around the crank. It started out without any noise, just something I could feel toward the top of the upstroke on the drive side pedal. Lately it is a clicking noise and it occurs more often when under more pressure such as going up a slight incline, not so much on the flat.

I checked to see if maybe the pedal was loose but it seems to be ok. I'm thinking it could be in the bottom bracket or maybe something in or near the derailleur being transferred to the crank. Or maybe the crank itself. I cannot seem to re-create the noise while the bike is on the stand.

Has anyone had a similar issue or have any ideas on what might be causing it?
Thanks