Sick 5 year old boxer...limping, stomach problems?

I have a 5 year old, neutred male boxer. He lives indoors, but does go outside to play in a fenced yard. He boards at a local kennel twice a yr at most. He has been experiencing a cluster of symptoms for the past 3 months. These symptoms come on without warning & one symptom is never present without the other. They last 2-3 days. The symptoms he has been having for the past 3 months are, Lameness in different legs (the limping/lameness changes legs, does not seem to be in pain when you touch his legs), a stiff-walk, low-grade temperature (rectal reading of 103.5), vomitting & lethargy, VERY loud stomach noises. He has no interest in food when he is experiencing these issues. I have seen two vets so far. The first vet refused to order blood tests to rule out any diseases. She informed me that it was not worth the cost. She did order A urine test & heart worm test. He was negative for heart worms, but blood was found in his urine. She then treated him with an antibiotic for a urinary tract infection. She also treated him for a stomach virus, as she believed that was the source of the loud stomach noises & the other symptoms. While on the antibiotics he seemed to improve. But, my dog was sick again shortly after that visit. I have since changed vets because I have a hard time believing that these symptoms are not related! Even when my dog is not having an episode, he generally does not seem well. He is also easily winded when playing. I do not care what it costs to run tests, my dog is a member of our family. The new vet ordered a series of blood tests (at my request) this morning, a urinalysis and stool samples, and xray were also done. He wants to rule out Lyme disease & other diseases. This new vet says that Lyme disease could cause these problems. Has anyone ever seen symptoms such as this in their dog or heard of anything like this? I have been up for two days now sitting w/ my dog (as he is sick again). He was sick when I took him in to see the new Vet this morning. I am waiting on his test results Wednesday. It feels like I've been waiting forever. I am VERY worried. If anyone has any suggestions as to what I can suggest my vet look for, please tell me. If they don't find anything in this current batch of tests, I don't know what I'll do or where to go from there. Any suggestions greatly appreciated.