Fussiness after 2 month vaccine

Hi mommies My son just has his 2 month vaccine on Wednesday and he developed a fever the next day which disappeared on the very same day. However he became very cranky on the 3rd day and his appetite has decreased quite significantly. He is not running a temperature. Should I be concerned about his lack of appetite? He used to drink 90-120ml every 2-3 hours but can now skip a feed and not even finish his milk!