When there is sewer gas smell around a newly reseated toilet, I would first suspect that the wax seal below the toilet did not get install quite properly. If this is your problem, sealing around the base of the toilet might only allow the sewer gas to travel through the void inside your second story floor. That might explain how the odor moved to the other bathrooms. Considering the facts you gave, I would suggest pulling that toilet up for inspection and a new wax seal. Good luck
