Unfortuately, absent any written contract of employment you are an at will employee and absent proof of discrimination against you because of your pregnancy/sex/race/disability, you will have very little if no recourse at all. As far as the "harrassment" over complaining about the chemicals that make you sick, this is a weak, but potential claim for hostile environment/harrassment based upon pregnancy/sex and before you can sue on it you must first make a complaint to the state commission on human/civil rights and the EEOC and they have to investigate to determine your right to sue.
Absent the discrimination claim, I am afraid you really have no other action you can bring as an at will employee if you were terminated over the customer's false complaint. However, if the complaint was false or unproven and you are denied unemployment, you should file an appeal because such complaints are not sufficient grounds to deny unemployment benefits, but it will still not get you your job back.
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