Obviously recurrent regurgitation & sickness should be assessed by a vet, but if your dog has been given a diagnosis of acid reflux then there are a few dietary changes you can make which may help.
A common sign of acid reflux in dogs is the vomiting of bile or regurgitation of undigested food shortly after eating.1 This may be due to a brief relaxation of the muscular opening at the base of the oesophagus (referred to as the sphincter), which has failed to ‘shut off’ the stomach from the oesophagus.
Not all dogs with gastric reflux will vomit or regurgitate though - some dogs will have much more subtle symptoms. Lip licking, air biting, teeth grinding or restlessness at night are often outward signs that your dog is uncomfortable because stomach acid has entered the oesophagus.
The general recommendation in these instances is to feed your dog a lower fat diet (9% or less), and to keep the protein on the lower side too. Protein can make the stomach more acidic which, in normal circumstances, is fine - but it may be tricky for an already over-acidic tum. Try feeding foods around 21% protein to see if that helps.
It should be noted that in rarer cases acid reflux can occur if the stomach is under-acidic too. In these situations, opting for a lower-fat food with a higher protein content may be more appropriate.
Lower fat foods may also be helpful for dogs that suffer with chronic gastritis (inflammation of the stomach), but again, there is no need to opt for reduced protein. Allergies can sometimes be the cause of chronic gastritis so opting for a good quality grain free, chicken free, beef free diet may also help (check your treats too!).