Weird reaction to telling super about pain disorder

I recently started a new job at a health care facility. My supervisor took me into her office and was showing me around the computer system when she brought up a patient file and the woman has the same chronic pain disorder as me. I took that open door to inform my supervisor that I was diagnosed with it as well. I literally just said, Hey, I was diagnosed with a chronic pain disorder. Her response: “Don’t tell anyone else.” Then she tried to clean it up by saying, a lot of people in our community that have it. I thought it was so strange and somewhat unprofessional, and I’ve been kinda distant from her ever since.

My reasoning for telling her was that I may need to take some days off abruptly due to pain, and on my last job, I told my supervisor and HR individually during my on-boarding process, and their responses were much more understanding. I was recently going through a patient file and found some paperwork about the disorder and learned it’s protected health information (I use proactive measures, so I rarely need to reach out for medical help, so I only go to my specialty for routine check ups). Even as PHI, it’s MY PHI, and therefore MY decision if I tell someone or not. I’m a grown woman 😂

So I’d like to hear your thoughts on if I’m being overly sensitive, or if my supervisor’s reaction actually was strange?