All you can hope to get under Tennessee law is fair compensation for your daughter's damages. What are her damages? Did she incur any medical expenses as a result of ingesting gluten? If she became ill, how long did it last? Good luck.
I am very sorry to hear of this terrible accident. You need to consult with a Memphis attorney to ensure that your rights are protected. In Tennessee, you have only one year to resolve your claim with the at-fault driver (or their insurance company) or bring suit. We have one of the shortest statutes of limitation in the country. You need an experienced attorney who can help you bring and resolve your claim in a way that fully accounts for all of your injuries.
In my opinion, you cannot take legal action based upon the facts you have provided. To succeed on a claim for slander, you will have to prove damages that are greater than being "bothered." Filing a lawsuit without having suffered actual damages would be frivolous and possibly actionable.
In most of my nursing home cases, I see nurse assistants get into bad situations when they attempt to cover up a situation. You need to keep good, contemporaneous records, do your job as best you can, speak up when you need something, and be honest and do the right thing. If you have had incidents with a particular patient, you need to make your supervisors aware, preferably in writing. Do all that you can to ensure that you are in compliance with whatever reporting system your employer has...