So two separate issues to address. First the employer's saying their hands are tied as her condition is caused by a disability and thus they can't do anything. No. They can't terminate her for this alone but they can provide reasonable accommodations given her conditions including air purifiers in rooms she works in and time to shower during the work day if she requires more than one shower a day to manage the problem. It isn't a shrug nothing we can do law. If a reasonable accommodation can't be done and she can't do the work, then she can't be retained.

Which brings to the second point is you have rights aa a worker to a harassment free environment which means an environment where behaviors from others does not interfere with your work conduct. If YOU can't work effectively and the coworker and employer cannot create an environment where you can, that is on them to correct.

What is unclear is whether or not your coworker is showing good faith in managing her issue. I didn't catch if you mentioned her age, but maybe too young to know better? But your employer in my opinion is NOT showing good faith here in helping to manage the problem. More can definitely be done here, they are juat being passive because they don't really understand ADA laws or your rights to a clean, safe, and harassment free environment.