Your blood work was done several months before the symptoms started, so maybe have that repeated to rule out a low
-grade infection. If you're not having fever, coughing, phlegm, or other signs of infection, I think it's unlikely. But it's a cheap test, and it has been going on a year, now, since that was done.
Also, as someone who has had an aortic aneurysm, I always think of the aorta. A thoracic aortic aneurysm wouldn't be expected in a young person, but it's not unheard of, either.