The teacher is out of line. I would meet in person with the principal to firmly and calmly express your concerns, and if you don't feel they are adequately address demand a 504 meeting with an advocate present, then go from there.
In my state you can't just draw up an IEP whenever, even if they have a 504. There must be testing to meet state requirements that demonstrates they qualify under an eligibility. There also must be documented interventions in general ed with limited progress to demonstrate a need for service. Despite any challenges or medical diagnoses, a student here does not qualify for special ed under an IEP unless there is a need for specialized instruction, rather than just modifications and accommodations to the general ed curriculum. I find generally that it matters less if you have an IEP or a 504 than if you have a good teacher and a supportive principal, frankly, which it sounds like you are lacking.
Good luck mama!!