Did they do enough?

I cannot say whether this facility is a good clinic or not. We brought our 8 year old australian shepherd mix in for having a cough and a swollen left paw, and in two weeks time our animal was euthanized. They could not diagnose anything and left it to cancer as the cause. Before we took him in, he was running in the backyard, running and jumping on the couches knowing that he was going somewhere fun to barely moving, laying down and not having the energy to do anything in just two short weeks. Initially, he went the first four days without any treatment except we could give him a cough pill. Then he was given carprofen which did very little while the vet determined whether it could be a fungal infection. When that test came back negative, it was determined to put the dog on prednisone and Augmentin. I don't know if they did that because I questioned to whether or not he had a bacterial infection. A few days later, he was given doxycycline and that is when the throwing up, panting and lethargy set in. That first day, Hilo had a temperature of 103.8. It wasn't until the last time we took him in that his temperature was normal. Two days later we had to put him down because we thought he was suffering. I am writing this because I am grieving the loss of dog. I do not understand in that short bit of time and almost three thousand dollars later that I am without him and I have this huge hole in my heart. That two thousand dollars paid for a couple of x-rays and a couple of blood draws to rule out things, but they never confirmed cancer. Mrs. Coleman just thought if it wasn't fungal then it had to have been cancer. I can't accept that. I think more should have been done to try and diagnose what was wrong with my dog. Maybe, I should have taken him to get a second opinion and paid another two to three thousand dollars for no answers, but that even scared me too. Now, I am just without my Hilo, and I am hoping he wasn't as disappointed with me as I am wit