Medical bills and concentrator

My husband Bradley Stowe has been recently diagnosed with (IPF) Idiopathic Pulmonary Fibrosis. He has been taken out of work indefinitely and will not return. He is also on home oxygen 24/7. He needs a portable oxygen concentrator which insurance will not pay pay. Inogen.com advised that we can buy one with life time warranty and a 10 Hr battery and cost would be $3691. We also lost his wages per week while waiting for disability to make a decision if he will qualify for disability. Any and all help would be greatly appreciated we have never been in this type of situation. We are also waiting for a call from Duke for a consultation to be put on a lung transplant. He also starts pulmonary rehab next week. IPF is a lung disease causing a lot of scarring in the lungs causing his shortness of breath which required him to be on oxygen. Please help if you are able.