Finding Strong Odor in Apartment?

I recently moved into a "luxury" 50 story apartment building and complained about a smell on day 1. It has been over a month and the smell is just getting worse. I get extremely ill when spending time in my apartment and it is driving me crazy not knowing what is causing the odor / my symptoms.

I have never smelt this type of smell before and it is very hard to describe, but someone described it to me as "wet cardboard". It is a very musty odor, with a tinge of pungently sweet, maybe a little chemically? Possibly a tinge of trash but it doesn't smell like trash / there is no trash in the apartment (I've been trying not to spend time in it since I feel so ill being there). It does not smell like sulfur / rotten eggs, does not smell like fish, does not smell like urine, and does not smell like a dumpster. I'm not getting rotten animal smells from it either really. I really don't know how to describe it.

I thought it might be mold, but I had a mold assessor test and they found the air sample to be within an "acceptable" range (even though there are no Federal limits). They did say that the possibility of non visible mold that wouldn't be picked up by an air test could not be ruled out, but the walls aren't currently harboring a lot of moisture.

The tenant before me had a dog, but the building completely replaced the carpeting and repainted the walls. I thought it might be VOCs because of this, but my $70 air monitor isn't picking up VOCs over 200 ppb (who knows how accurate this cheap device is though).

I am experiencing several symptoms: extreme migraines, chest tightness, trouble breathing, brain fogginess, extreme fatigue, etc. When I leave my apartment for an extended time my symptoms get better. I have an autoimmune disease so I could be more susceptible to whatever is causing this?

The building was built in the 1960s and was vacant for 10 years until it was recently restored ~5 years ago (including a very large asbestos abatement project). One concerning thing I did notice is that behind the sliding doors in the apartment (I have 4 sliding doors) there is tons of dust / debris that look to be from the old, unrestored building that they just left there. Photos attached.

I am so miserable / traumatized / feel dehumanized trying to fight a multi billion dollar apartment company who refutes that anything is wrong with the apartment and is telling me to just get over the smell. I've already spent thousands of dollars on hotels and testing and I feel so defeated - any suggestions/insights are much appreciated. Thank you!