Hello- Thank you for asking the question here at JustAnswer. I have read what you have written and am happy to respond.
This is a very interesting question that most would probably dismiss.
It is true that research has indicated that people found to have brain tumors have reported have a strange smell like rubber. This has been verified in a number of studies. See attached:
You will see at the bottom of the list: "Strange Smelling Odor"
I certainly would not dismiss this and encourage your ex wife to see a Neurologist for further evaluation.
I trust that this has answered your question and wish you the best,
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