I see. Again, I am sorry to hear about your situation. The fact that it was not serious and only a day's absence means that it wouldn't likely be a "serious medical condition" that is covered by FMLA. That was really the one thing that I was grasping at anyway, but if she didn't even get in to the doctor then that's most likely not an option. The final regulations provide examples, in section 825.114(c), of conditions that ordinarily, unless complications arise, would not meet the regulatory definition of a serious health condition and would not, therefore, qualify for FMLA leave: the common cold, the flu, ear aches, upset stomach, minor ulcers, headaches other than migraine, routine dental or orthodontia problems, periodontal disease, etc. Ordinarily, these health conditions would not meet the definition in 825.114(a)(2), as they would not be expected to last for more than three consecutive calendar days and require continuing treatment by a health care provider as defined in the regulations.
In the absence of any exception or written employment contract or written employment policy that gives her a right to some employment, her employment was "at will", as Oregon is an at-will employment state. At-will employment means that without a contract, you have no contractual or other right to employment with the company. The company is entitled to fire you for any reason: a good reason, a poor reason, or no reason at all--as long as the company does not fire you for an illegal reason (race, gender, age, religion, etc...). But it extends beyond firing, to hiring, promotions, demotions, wage cuts and raises, disciplinary actions, and even scheduling. Unless you can show that this was done in violation of a contract, union agreement, or a clear violation of an unambiguous and binding clause against the employer, or that it was done because of some minority status (age, race, gender, religion, disability) that you have, then they do have this discretion.
Because FMLA would not apply, and assuming that there was not any evidence of illegal discrimination (age, race, religion, gender, disability) then I'm afraid to say that what they did, while illogical, immoral, and unethical, was not illegal.
I know this is probably not what you wanted to hear, but it is the law. I hope that clears things up anyway. If you have any other questions, please let me know. If not, and you have not yet, please rate my answer AND press the "submit" button, if applicable. Please note that I don't get any credit for the time and effort that I spent on this answer unless and until you rate it positively (good or better). Thank you, ***** ***** luck to you!