S.H.
Is he congested? Maybe he has a bug? How long has this been going on? We know our bodies better then anyone even at 9 months old. If he doesn't feel well he may not want to eat. If you force him you may end up with a sick stomach. If he goes longer then 48 hours I would take him to the pediatrician. If he is congested he may be avoiding eating in order to breath. Have you recently started any new foods? Sometimes it takes longer to break the new stuff down and he may feel fuller. Good luck!