No one here can give you legal advice. You'd need to consult a licensed attorney in your state for that. The lowest price point there may be a call to your state's Protection & Advocacy system Disability Rights California. These offices have enabling statutes that allow them to represent disabled individuals. The process may be frustrating, or not, DRC appears to be more robust than other state P&A, but you must go through intake in order to be reviewed for attorney assistance.
Our child never signs what the district believes is an enforceable, viable contract and/or consent of a minor. I always welcome them to choose wisely in response. As an aside, many here will revert or cite federal laws which is never a bad starting place, but federal law and associated administrative agencies with jurisdiction for enforcement are not necessarily the response you need or are looking for. State laws may raise the federal floor, and going forward without licensed counsel knowledgeable in applicable state laws may not be in your best long term interest.
My advice would be trying a quick Facebook inquiry to Allergy Law Project. They won't give you legal advice but you may get some solid leads for a plan moving forward. Mary and Laurell might also have some interest in this fact pattern or recommendations for an attorney in your state. Won't cost anything to try. Might want to tag FARE on social media if you either desire to or even have social media. Be measured with what personal details you give out publicly. In fact, I'd advocate a discreet direct email to someone at FARE with the appropriate job title but I understand most people prefer Facebook or Twitter.
In my personal opinion you would benefit from having a competent, licensed attorney in your state to guide you through this as a consultant, one who has proven experience in this nascent area of law (allergy/disability). I'd be cautious in agreeing to full representation with a required retainer (significant money down) but a free initial consult followed by agreed hourly consult until representation seems sensible to both parties could provide good attorney oversight with the benefit of "issue spotting" for long term outcomes.
Of course you may hit the lottery with DRC P&A where they agree to take your case because it applies to a broad segment of disabled students with adverse impact, among other troubling issues I won't enumerate.