My dogs not well and I can't afford the vet bill's?

I know alot of people will be judge-mental straight away and say "why did you get a dog if you can't afford it?". So to them let me explain..... Yes I could afford it but was not prepared for all the problems I was to encounter I bought my German Shepherd 18 months ago, I did every bit of research in the books to find a good breeder and choose a healthy pup. finally I found one and believed I had bought the perfect pup. The breeder told me the dog had no hereditary problems as the parents and grand parents had no problems and my pup had come from a good bloodline. Her dogs also all had pedigree papers. I met the pup and his parents and all seemed well After six weeks of having the dog at home I started to notice he was coming up in rashes on his body, so I took him to to the vets. The vet told me that the dog appeared to have atopic dermatitis, which could possibly be a life long problem. The vet gave my dog flea treatment, antibiotics, steroids and told me to complete the course of medication. I also bought my dog a hypoallergenic bed. After about 3 weeks of treatment the rashes cleared. Since this started up until 4 months ago (about november 2010) I was going to the vets every 2 months at least to get more antibiotics and steroids. I was also recommended to have groomed by the vets with a medicated shampoo every 2 weeks. During this time he also had occasional diarrhea and usual medical problems you might encounter with dogs. When the dog was just 6 months old on a routine visit to the vet, I found out that my dog only had one testicle and the other one was stuck in his abdomen. They had to operate and this cost alot of money. At the same time they also told me he had poor formation of his back legs and hips and was going to be highly prone to hip dysplaisia. They recommended that I give him fish oil capsules and Glucosamine with chondroitin daily. Not good news! but i kept my head up high and continued on. My wife gave birth to our second daughter last june. Expenses were lots and money was tight. I went to my vets last November and we decided to try him on a hypoallergenic expensive diet. it worked up until early in the new year, then he came up in rashes. He was put again on another course of antibiotics and steroids. During this time I changed his brand of hypoallergenic food to another brand and so far so good with his skin. I was told that prolonged usage of steriods was not good and could possibly shorten my dogs life. I love my dog so much but I'm struggling. He was very sick yesterday. He WAS vomiting white foam, he would not eat, he did not want water and kept hiding in my daughters room. I took him to the vet this morning and the vet said she could feel something hard around his abdomen area. She recommended I have him x-rayed and if necessary operated on. If operation necessary it would cost upto �4000. This shocked me, I was stunned. I am in a dilema, I don't have that money. Life in London is expensive already when you have a family. I've had a few problems that have affected me financially over the past year. I did consider vet bills when buying the dog, but have been really unfortunate with him having so many problems. Has any one any good advise for me, pls help!