I hope she shared with her GP everything that is going on with her symptoms and the difficult time she is having struggling to stay working.

Laying the groundwork now, even though she is still somehow managing to haul her butt to work may help her case when she realizes she can't do it anymore. Perhaps her GP could document the severity of her tremors, her insomnia, her mental status, her vital signs and labwork now....while she is stressing her body to the max. She might show some improvement in symptoms when her body is getting more rest.

Landscaping is also difficult manual labor. Perhaps she could work at something less strenuous.

If she can't work at anything, help prepare her mentally (and financially, if possible) for the lack of income while she waits for SSDI approval. As Janke mentioned, even if your gf were to be approved right away, she'd have a minimum of 5 months of no income. She'll also have to think about getting COBRA coverage for health insurance, as Medicare doesn't kick in until 24 months after SSDI finds you to be disabled.

It is critical that she be totally honest with all of her docs about her difficulties in working. If she has been lax about scheduling appointments, she needs to get on that NOW with frequent follow ups with her GP, a psychiatrist/psychologist and a neurologist. She will need thorough documention from them to support a claim.