Hi there, you are through to Dr. Jake. Im a UK based vet. Im sorry to hear of your concerns with your dog, Boris.
The signs he is showing could be due to a few reasons:
1) salivation and fatigue can be a sign of feeling sick nausea - dogs often excessively salivate , can sometimes gag and retch , they can stretch out thir front legs in whats called a prayer position if they have abdominal pain. this often results also in not wanting to eat like what you have described. causes of this include gastritis, ganstroenteritis, pancreatitis and can often be coupled with diarrhoea. the tongue movements could be him panting because he is unsettled and often this can be pain related
2) this can be a sign of licking something that doesnt taste very nice - for example a dog that has tried to eat a toad or frog or even a slug outside tastes horrible and leads to excess salivation , this can also happen if a dog has licked something caustic such as washing soda, cleaning products, chemical in the house
3) this could be a sign of something stuck in his mouth or oesophagus - this often presents as not wanting to eat, excess salivation, abnormal mouth movements or tongue movements, there is usually history of playing with a stick or a stone, or someone having a barbeque and them having skewers or similar which meat has been on that the dog has stolen unknowingly. this can often result in trauma of the mouth and cause a bad smell if infection is present.
4) another cause of this could be dental disease and dental pain , causing infection though this generally doesnt cause them to stop eating
if you think he has an ear infection it doesnt really fit with the signs you have described though there could be more than one thing going on - signs of an ear infection usually cause head shaking, scratching, , dirty ears- it can put them off their food but only in severe cases and could be related to the panting you have mentioned
I would recommend an appointment with the emergency vets today if your general practice isnt open. they can perform a full exam , especially to look into the mouth to see if there is any evidence of a foreign body or trauma , they can perform adbominal palpation to feel to make sure the abdomen feels normal and check his temperature to make sure he isnt running a fever and provide appropriate medications if required. they may recommend sedation and oral exam to check very far back in the mouth if there is suspicion of something stuck in the mouth
i hope all this information helps