Please help save my Service Dog

This is Hercules , he is  140 lbs. and 31"at his shoulder and only 18mos. old and still growing he is AKC reg. purebred German Shepard he has been certified as my Service dog . I had to get him fixed and after the vet tells me only 1 testicle had dropped which I had all ready known then he says the he needed a ultrasound to find the other one so I did and it was found deep inside his body and the vet says it has to be removed or it will turn into cancer if not taken care of soon ! The cost so far is 1600 then he will have to stay in the hospital a day or two then he will have to have meds. and the cone of shame , biopsy of the tissue . I am disabled and have had 38 surgeries 5 total knee replacements and just had my neck fused from my brain to my chest , diagnosed with spinal degeneration was a 11:30min surgery .I was having such a horrible time getting around from the pain and the pressure on my voice box has caused me to have trouble speaking ,I was told to get a service dog to help me get around and feel more comfortable around people since I will never be able to move my head, Hercules is such a wonderful service dog helps me walk and give me someone to love and feel loved ,he is called the gentle giant by everyone that comes in contact with him and brings such joy to all he can also pick me up when I fall and stand steady so I can brace myself when my balance gets bad ,which has gotten really bad since my spinal surgery. My SSI barely gives me less than 1035.00 to live on which puts me below the poverty level ,last year I spent over 3000$ on his vet bills I had to skip meals every so often and have been trying to buy a used car to fit my best friend in a pruis with 300000 miles on it takes any money I can spare   until I  can afford something bigger and more reliable Hercules comes first I try to walk as much as possible but artificial knees can only get me so far , I have Never let myself ask for help before but it has finally cost me so much damage to my body that the final spinal surgery has put me in a place I never thought I could be I will never give up but PLEASE don't let me best friend Die even a Prayer will be greatly appreciated!!God bless