Mucous in 2.5 month old poop

Ems

So ever since the day before? Day of? his immunizations (8 days ago) my baby has been having mostly mucous diarrhea like stool 1-2 times a day. Only 1-2 times in last week were his stools a bit more seedy. They even smell like diarrhea. He has been eating a lot less during the day but that started 2 weeks ago. Only 5-10 min a feed daytime and about 10-20 min at night. Feeding about 9 times a day. He has enough wet diapers. He does seem a lot more fussy and gassy. My let down can be overactive at times causing him to gulp down air as well. Should this be concerning the extended loose stool? And what would cause it? Should I see his doctor?

Thanks!