Well.............I am not the expert on vaccines but any means but I do not that with these little guys it is not a good idea to give the combination shots. Some on the board also advocate for titer testing to check their immunity levels prior to revaccinating/boosters. How old is your pup and how much does he weigh? The smaller they are the easier for them to dehydrate.
I personally would be worried about dehydration. How do his gums looks---are they pink or are they white? White is a sign on dehydration and the ER vet is needed immediately. I wish someone with more experience would come on to offer better advice. Is he still throwing up? You can also offer thinks like canned pumpkin and plain yogurt as well as a little boiled chicken and rice to help settle an upset tummy. I believe Pedialyte has been suggested in the past as well. I'm sorry that I cannot be more helpful but the last time one of mine was sick I was able to take them to my regular vet because it was during the week.
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