I'm Trying to get my sons brain tumors removed

My son is 20 he currently has one inoperable brain tumor and one operable tumors and stage 3 lung cancer he's currently receiveing treatments for his cancer but we don't have the money to pay for the removal of his brain tumor witch causes his seizures and the tumor has been growing and his seizures have been getting worse and more frequently happening it randomly happens or if he over heats or if he hits his head he can be sent into a seizure please I'm begging for some help