It is normal for SSDI to turn down the first application. 80% of first time apps are denied. Her doctor does not determine her disability. The SSDI Blue Book sets the standards. Likely, she cannot maintain the Pace and Persistence of a job. Has she contacted an SSDI attorney ? They get paid a percentage of her back pay with a maximum limit (25% or $6000, which ever is less )

If she has the same neuro doctor who said there are no tests, she needs to find another doctor. A Neuro Psychological Assessment can tell a lot. A DTI MRI can show problems. An fMRI can too.

Medi-Cal should be easy. It just looks at income. The Kaiser Medi-Cal should not be hard to get. But, if she can afford the $80 to $100 per month to get the non-Medi-Cal health insurance, she may have access to more services. I have family on both systems. She would need to inflate her income to $16,000 to get the better plan then it will cost a bit.

She should have some medical records for her SSDI application. Did they award her SSI payments when they denied her SSDI ? The SSDI app includes an application for SSI. It is a stop gap payment system for those with no other resources.

For her future medical needs, her history does not matter so much. With concussions you treat the symptoms, not the medical history.