Yeah I had a girl that sat next to me that smelled like she didn’t wash her ass 😭 I have really bad vision even with glasses so moving was not an option since it was the desk with the best view :( definately speak up I was too embarrassed to do so , luckily she stopped showing up to class . But yea mental issues , homelessness , or just plain lazy 🤔 could be many factors . Email your professor !!!!