What Causes Headache,nausea And Vomiting After Being Bit By A Dog?

my husband got bit by a dog yesterday, not deep but left a puncture- they put him on augmentin, last night he started having a headache and today vomiting with severe nausea, headach and now fever 102; he was in ER- they think its gastritis cause his CT showed inflammation. Could this be a reaction t the dog bite? Apparantly the dog had his shots.