Where did the Queen go???

I check my older hive yesterday, wanted to see if they started to fill out the honey super. No, they have not even started it, even worse, the population is down. I wondered if the swarm was from my hive. Due to the lower # of bees, I went though the upper deep. The middle 6 frames have honey in them and empty brood cells. Completely empty, no eggs, no larvae. Not good. I also had expected the outside frames to be filled with honey by this time.

I lifted off the upper deep and looked at the lower one. I found plenty of drones, I checked all but 3 of the frames, the bees were not happy with my intrusion so I skipped the rest. About 5% of the brood cells were capped, the rest were empty, no eggs or larvae there either. I did not see a Queen, but I'm not quite sure what she looks like. I also might have missed a queen cell. I hope so. I'll email the guild about getting queens, see if anyone has any. If my colony swarmed, the queen would have hatched soon or will be.

I'll check back next Sunday. If there are no eggs by then I'll get a queen to install. argh.

EDIT: Swarms can be caused by lots of things, I'm thinking there is not enough pollen/nectar and the hive is stressed from this.