Our toilet is 3 years old. We have had this problem only 6 months. When we flush, there is a sewer odor. It is especially strong after the first flush in the morning. A plumber pulled up the stool and put in a new wax ring. Since then, the odor seems less during the day, but is still there and strong in the am. Any suggestions?
Your plumber is going in the right direction. Sewer gas is getting past the water seal of the trap or coming out elsewhere. More investigation in the area is necessary to find the leak that can be coming from anywhere in the area – an unsealed joint in the vent, a crack, etc. The techniques for finding a leak, smoke testing, etc. are beyond the ordinary. Ask the plumber to keep going until the smell disappears, that is both the art and science of the purpose of his expertise.