You can get mold test kits for pretty cheap. Best way to find out, and deal with the landlord if you do. Have receipts showing the mycotoxin levels in the air.
They say 25% of the population are very sensitive to toxic mold. I'm one of them for sure. Black mold is like a hidden disease that will destroy your life, while other people around you will just think your crazy and seem unaffected. You literally have to rip open the shower walls and pull a moldy peice of sheet rock out and be like "see i f#$%ing told you so". They still don't seem to care, including family members.
I know for a fact almost 1/2 the homes anywhere have black mold in some location.
Anyways.. some things I found helped out (before ripping apart an entire bathroom) was to make my own home air filters for pretty cheap.
I would take $18 walmart special 20x20" box fans, and use metal tape to stick a 1''x20''x20" furnace filter to the back. Get the best filter you can that is rated for mold spores. Run 2 of them on low to circulate the building, and change the filters every 2-3 months.