Connie;
I ask myself the same questions all the time. My wife had mononucleosis and about 4 years later she was diagnosed with lymphoma. About the same time I was diagnosed with SCC of head/neck with unknown primary. We are both
HPV negative but are both positive for Epstein Barr virus (EBV) which is also causative in both lymphomas and oral cancers. I guess that we'll never know. You are wise to take precautions. I don't know if there will ever be a way to determine if your and your husband's cancers are related. Oral cancers can be caused by so many things and some are simply a result of bad luck with no identifiable causative factor. I'm glad that you are clean and moving forward.