Help Thunder Emergency Vet Bills

We're really desperate for help. Our dog Thunder has been super sick and not eating since Wednesday. He's lost over 20 lbs.Throwing up bile. Took him to the vet Saturday which we could barely afford. Brought him back again today.$700 bill for meds, blood work, x-rays and they discovered a huge mass in his intestinal track they think it could be a tumor. Dr's recommend an ultrasound and possibly emergency surgery. Thunder is everything to my wife and I and our 4 kids, and has been nothing short of a blessing. We transferred him to an urgent care facility now. We're not going to be able to afford the ultrasound and any additional treatment he may need. If there's anything you can do to help or spread the word to help, we would be forever in your debt. He's family to us and I don't want to lose him. I just don't know what else to do. Wife and kids are crying and everyone is nervous. 

Update: Just finally got Thunder seen. Had to pay an additional $500 that we borrowed from family just to start the process for an ultrasound. We've already spent our mortgage payment to get him this far.

Please, please, please, if you can give anything, we would be greatly appreciative. Thank you so much. God bless