I am sure you are worried about Diesel not feeling well, I am sorry. In response to your question, excessive drooling is a common symptom when dogs are having gastrointestinal issues or even part of a systemic disease. The big question in this case and that may explain his lack of appetite and vomiting is: Why is he drinking more than usual? You see, when a dog drinks more water than usual it is a sign of an underlying medical problem. There are many possible causes. It will be difficult for me to determine the exact underlying cause without a hands-on examination and some testing. But, common causes are an active infection, hormonal disorders (diabetes, cushing's), kidney or liver disease, pancreatitis, and even cancer to name a few causes. Unfortunately, of all these diseases have similar symptoms and can not be differentiated on history only. To determine which of the above is the underlying cause your family veterinarian will need to do some blood work (chemistry profile, T4 & CBC) and urinalysis as an initial screening test. Sometimes we need the use of imaging like x-rays or ultrasound to reach a definitive diagnosis. Treatment for Diesel will be determined by exam and test results. For example, if this is related to an infection he will need antibiotics, if related to pancreatitis he will need to be hospitalized for supportive care and medication, etc. Unfortunately, we are very limited as to what you can do at home, I am sorry. I would strongly recommend having him checked this morning by your family veterinarian. In the meantime, this is what you can do for the vomiting:
1- Do not give things like Pepto Bismol or Imodium. Start him on Pepcid AC (famotidine) 20mg tablet every 12 hours. You can buy Pepcid AC over the counter in any pharmacy.
2- No food or water for 4-6 hours. Need to give his gastrointestinal tract time to rest.
3- After 4-6 hours offer a small amount of water. Wait half hour, if no vomiting, you can continue giving him water every hour or so. Do not let him drink excessively. Leave him without food for 8-12 hours then offer a small amount of rice (50%) and boiled boneless chicken or ground beef (50%) 4-6 times a day.
4- Follow up with your family veterinarian for a hands on examination. If cost is a concern look into your local ASPCA or Shelter where they often offer veterinary services at a lower cost.
My goal is to provide you with excellent service - I hope I've provided the information you were seeking, if you feel you have received anything less, please reply back as I am happy to address follow-up questions. Kindly rate me when you are done.