People keep telling me I’m too young to have my condition

I’ve always been a lurker and never posted on here, but I’m just so frustrated I need to talk about it. I’m 21F, and I’ve been dealing with chronic knee pain for a long time. It had no clear cause, I’m not obese, an athlete, or any other risk factors for knee pain. Sometimes it would get so bad I would limp, and it would be affected by weather changes. My knees would be swollen in the mornings sometimes, even if I did nothing the day before. Long story short, I was diagnosed with rheumatoid arthritis. It’s rare for people my age, but it’s not impossible. Several family members have it, so it’s probably my genetics. Most people around me knew about my knee pain to some extent because I would make a comment about it frequently (ex. Dang my knees hurt). Ever since I got this diagnosis, people have not held back on their comments.

The day I went to work after I got the diagnosis, a couple coworkers asked how it went. (I’m not super close with them, but we’re friendly enough to talk about stuff like this. I’m also the youngest in the building by far. My boss is 75 and most of my coworkers are at least 40. Not that it matters, I’m just way younger than all of them. I also told them I was going to the doctor for it.) I’m serious, every single one I told said somethings along the lines of: “But you’re way too young for that! There’s no way you could have that!” “But you’re a baby!” Several family members have also (when I told my dad he called me a liar) the only ones who have been supportive are my mother and partner. Even my grandpa who also has it made a comment! I was kinda taken aback by this, I have gotten little to no sympathy. One of my coworkers has actually started playfully teasing me about it now. Not that I expect people to feel bad for me, but they asked me how it went, so I told them. I’ve felt so invalidated, like my condition means nothing because I’m young. I know that, I know I’m young. But I can’t just make my arthritis go away? I never know what to say to people when they make comments. It’s hurtful and frustrating when you can’t even get a simple “oh I’m sorry that happened to you.” And instead, you basically get indirectly accused of lying. I never claimed to be the smartest and wisest human on Earth, I know I’m far from that, but I’m also not an infant. You don’t have to be old to get arthritis, and I’m living proof of that.

I can’t really talk to anyone besides my mom and boyfriend, and I know they’re sick of hearing me rant. So I just needed to rant somewhere else. Thanks for listening.