Help with medical expences

My mom was diagnosed with stage 4 inflamatory breast cancer last month . I have been trying to help with some of there copays but it is getting out of control...My parents are on SSI and have Humana as a health insurance and Humana says they are responsible for the first $5,750.00 and we are only at $1,700.00 . I have applied at a few different charity foundations but so far nothing.. If you can help it would be greatly appreciatied .... thank you