these changes are mainly because of the teething phase, as your baby will be quite uncomfortable, hence refuse to feed or eat.
also, some babies feed for longer but some stop early. for instance, my first one didnt stop even till age 2, while the younger one stopped herself completely by the time she was 10 months old. if your baby's doc says its fine then i am sure it is alright. unless your baby is losing weight or is lethargic, i dont think you need to worry.
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