I have 2 bedrooms on a single breaker, and just yesterday, the breaker tripped. No devices are plugged into any outlets. Both rooms have ceiling fans (with lights). Both rooms have 3 wall switches. 1 for the ceil fan's fan, 1 for the ceiling fan's light, and 1 controls the bottom-half of one of the wall outlets. If all 3 switches in both rooms are off, I'm able to reset the breaker. In one bedroom (bedroom A), all of the outlets work fine (testing with a night-light). In the other bedroom (bedroom B), one of the outlets works, but if I plug the night-light into any of the other outlets (there are 3 others), the breaker trips. I have replaced these 3 outlets, but no change. I have also tested all outlets in both bedrooms with an outlet tester tool, and I get "correct" on all of them. In bedroom B, 2 of the 3 "suspect" outlets have 5 wires going into them (2 hot, 2 neutral and 1 ground); the 3rd "suspect" outlet just has 1 hot and 1 neutral (and 1 ground). If I completely remove/disconnect the 2 outlets in bedroom B that have the 5-wires, and just leave the wires dangling in open air, then Bedroom A is completely fine (ceiling fan and light included). In Bedroom B, the 3rd "suspect" outlet is off, and the other outlet (the one that always works) still works. The ceiling fan and light in bedroom B do not work; switching on bedroom B's switches does nothing; the breaker does not trip. With those 2 outlets in bedroom B completely removed, there's nothing I can do to cause the breaker to trip.
Another data point: with all the outlets connected/installed, in either room, attempting to turn on the ceiling fan or ceiling fan light cause a trip (so, plugging something into bedroom B's 3 "suspect" outlets is not the only way to cause the trip).
I've visually inspected the wires in bedroom B's 3 "suspect" outlets, and they all look okay; I don't see any rips/tears in the wire's insulation, so I don't think there's a short or ground fault.
So I'm completely baffled, and I want to make sure I've tried as much as I can before I commit to calling an electrician. What's strange is that nothing has "changed" in the past couple of days; I haven't nailed anything into any walls, and I have plugged anything out-of-the-ordinary into the outlets. The house was built in 2008, so "old" wiring shouldn't be an issue.
Thank you very much for your time. Any suggestions would be greatly appreciated.