Oh dear! Poor Boo. I'm afraid this looks quite serious, and definitely needs veterinary care - this is not something that can be treated with home remedies.
If getting Boo in the car is an obstacle, you can call around to some clinics in your area to see if there are any veterinarians near by who are able to make house calls. If not, you may need to enlist a friend or neighbor to help you get him in the car for transport. If you're concerned that he may bite you, you can get a muzzle at most pet stores to put on him before attempting to load him in the car.