Parent needs medical treatment while visiting the US

Mother is visiting US currently for a couple months (she's on tourist visa, no green card, me a us citizen). She has a form of basic traveler's medical insurance from WorldTrips.com (excludes pre-existing conditions but seems to cover upto $2500 for "acute onset of pre-existing conditions", specifics cut-pasted below).

She has gastrointestinal (lack of hunger/stomach pain) and spine issues (herniated/arthritic lumbar disk) that became severe here. It may need specialist/tests/MRI etc. The doctor abroad had allowed them to travel for this visit.

Anyone got treatment using such insurance from specialists/gastrointestinal/colonoscopy/MRI/neuro-spine without huge bills? Any inexpensive clinics/ways a parent of US citizen can get treatment?

Even with self-pay a specialist visit at most places in the SF bay area requires referral and it's hard to get it on short visit.

Location: SF Bay area, California

Edit:

The insurance doesn't cover pre-existing condition but covers acute onset of pre-existing condition. Not sure if this would cover a visit to though as it disallows chronic condition but still allows acute onset?