Well my little puppy is a bit...sensitive.
He has always been this way. Whenever company leaves on Monday he would be in such a depression. But when we went on vacation for a week, wow it look him a long time to recover.
He wasn't eating and was actually puking a lot. I gave him some milk with his food which has always helped him. However, that is expensive.
So, in order to keep his tummy okay & full and our pocket books okay and full I just added water instead of milk. Seems like a simple solution however I didn't think it would work and boy did it!!
That might work for you and your pup.
ps. another great benefit is our dog didn't have the usual gas afterwards...yeah!!