I've got a 20 amp breaker that keeps flipping, it has 3 outlets, 3 sets of indoor lights and 2 flood lights on that breaker. Last couple weeks we noticed that we'd come home and the breaker would be flipped. I'd flip it back on and it might work for a couple days or a week, then it would flip again. I thought maybe it was because of something my wife had plugged in to one of the outlets. So I've unplugged everything from the outlets turned all the lights off and it still flips, but now it flips in 30 seconds. It's a new home and has worked fine for 4 years until now, What can I do to figure this out?

If the flood lights are on a timer, turn the timer off and leave the floods of for a few days.

You might want to have a licensed electrician take a look at the circuit. A 20 amp breaker should not trip with the load you are describing unless the big load is the floods. Just out of curiosity, what is the amperage required by the floods?