Welcome to Just Answer, I will do my best to help with your problem
This is probably either a venting issue or possible a stoppage in the main sewer line
Are you on city sewer or septic?
Then you best course of action would be to call in a drain cleaning company to snake the main line or call in a plumber who can snake your sewer and look into the possible venting issues
Ok, I'll try that. But I do have another toilet just in case. Thanks.
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