Baby won’t latch unless I stimulate letdown with pump first… anyway to get back to normal again?

This issue started about a month ago where he would latch and drink a bit, then come off and cry and scream until I moved him to the other breast and then the cycle would repeat.

It never happened at night time or in the early morning and there were odd occasions it wouldn’t happen but then it started getting worse and more consistent.

The last week it got so bad I’ve been in tears most days and then I found out he hadn’t gained weight in a week.

Today he wasn’t latching even for a few seconds so I stimulated my letdown with a pump for a couple minutes and then latched him, he then drank from both breasts until coming off satisfied on his own.

So he won’t suck to stimulate my first letdown or sometimes won’t wait for second letdown, especially in the afternoons and evenings.

Is there anything I can do to get back to where we were? He used to be such a good sucker and cluster feeder :(

My partner thinks using a pacifier may have caused this, what do you all think?