Roman the Great Dane lump removals

My beautiful gentle great dane Roman went in to the vets as they needed a blood donor dog urgently to save another dogs life. When I picked him up the caring vets had removed 4 lumps which i was not anticipating. My insurance company denied my claim and have left me trying to come up with the funds to pay my vets what is owed. My lovely boy can not have anymore treatments while my bill is outstanding which is causing me great worry and stress. My boy is my soul dog but I was not expecting or anticipating this and as I am now the financial provider of my elderly parents due to covid. The bill is not within my reach.
I have no where to turn and have never asked for help before but am dropping my pride and asking for help please xxx