16 weeks temp of 37.8 & not drinking as much

My son had hes 14 week shots a day ago (dates are off as he only had hes first vaccine a week and half after birth due to jaundice) anyway .. I've been monitoring hes temp it's been jumping between 37.4 to 37.8 cant seem to get it down and keep it regular, hes also not drinking as much as he normally would during the day, he didnt even want to drink hes bedtime bottle after bath now.. he just went straight to sleep other than that hes acting hes usual self.

Should I go to the hospital?

Its 7.30pm here and no docs are open so only option is the hospital

Advice?