Remy, I admire your resolve to not give up and to continue to search for the underlying cause. It sounds like your neurologist is also working hard with you.

If you choose to pursue consulting with Mayo Clinic experts, you may wish to look into financial assistance https://www.mayoclinic.org/patient-visitor-guide/billing-insurance/financial-assistance

To get Mayo Clinic expertise closer to home, consider partner health systems in California with the Mayo Clinic Care Network https://www.mayoclinic.org/about-mayo-clinic/care-network/about
The Mayo Clinic Care Network is a select group of independent health systems that are granted special access to Mayo Clinic's extensive knowledge and world-leading medical expertise.