Appeal or reapply?

Thanks in advance for any advice you are able to give. I am helping my mother (62F) apply for SSDI benefits. She is self-employed and has been experiencing symptoms from her cancer for years, but she wasn't diagnosed until this November. Directly after her diagnosis, I applied for SSDI, SSI and early retirement. Her diagnosis qualifies her for a Compassionate Allowance. Since her disability has affected her ability to work since January 2024, I set that date as the date of onset of symptoms. After providing financial information, they determined that she exceeded $1,550 minimum requirement (which is true) and denied the claim for SSDI.

Now, I'm unsure whether to appeal or simply reapply using a different onset date? Since her diagnosis, she's been in inpatient treatment every two weeks, and has passed all of her work off to team members who are handling her clients. I'm not sure if she will be compensated for those clients during this time.

Any advice on what to do?