I am sorry that you are having this problem with your dog. In response to your question, when a dog drinks more water than usual it is a sign 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, I am sorry. But, common causes are an active infection, hormonal disorders (diabetes), kidney or liver disease, ingestion of a foreign body and even cancer to name a few causes. The fact that she has a history of possibly eating a piece of foam, is not able to defecate and is vomiting I would place an obstruction high on the list of possible causes. In other words, the foam may be obstructed in the intestinal tract. If she does have an obstruction and goes untreated this could have a fatal outcome. For this reason, I would strongly recommend having her checked tonight by ER veterinarian, do not wait. Unfortunately, there is not much I can recommend for you to try at home that would have any significant therapeutic benefit, I am sorry. I realize that this answer may not be entirely to your liking, and I regret being the bearer of information that you really don’t want to hear. But it would be unfair to you and unprofessional of me were I to provide you with anything less than truthful and honest information. I hope you understand. If you do not have access to ER vet this is what you can do until she is seen in the morning by your family veterinarian:
1- Do not give things like Pepto Bismol or Imodium. Start her 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 3-4 hours. Need to give her gastrointestinal tract time to rest.
3- After 3-4 hours offer a small amount of water. Wait half hour, if no vomiting, she can continue to have water every hour or so. Do not let her drink excessively. Leave her without food until she is seen by your vet in the morning.
4- Follow up with your family veterinarian for a hands on examination, blood work, and x-rays as an initial screening test in the morning.
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.