Hi, Tannilisa, and welcome,
I'm not a medical professional (and I don't think any of us here is). But most of us have learned a bit about nodules and lymph nodes. Lymph nodes react to infection/inflammation, so the enlarged lymph node might be related to your pneumonitis. And a 3 mm nodule is very small--most nodules are not cancer, and it might be related to your inflammation or it might be scar tissue or something else. Usually nodules that size are simply monitored and re-checked a few months later. That's essentially what will happen if you go for another check in September.
Bottom line, it isn't something that should cause you to freak out. You're not ignoring it (which is good), but in all likelihood it will turn out not to be anything to worry about.