I can completely understand your situation and I been through from this position recently. And, it is very difficult to see your dog in such condition.
According to me, go to the vet so that he can advise you appropriately. Because recently I have lost my dog due to certain health issues and then after a while I went to britishgritjackrussellterriers.com to buy a new pup so that we feel can stop missing him.
There I found a person whose dog was not well, so he updated me that he took his dog to the vet and after proper medication his dog was perfectly fine. But he updated me to take care about some of the symptoms like:
Excessive drinking or urination
Dry or itchy skin, sores, lumps, or shaking of the head
Coughing, sneezing, excessive panting, or labored breathing
Bad breath or drooling
Appetite change associated with weight loss or gain
Frequent digestive upsets
So these were the things which he said and if such happens to your dog then you must take your dog to vet.
And don't worry your dog will get perfectly fine
All the best and take care of your dog