So glad you've posted this, I'm going through exactly the same thing. Last week my LO started hysterically crying each time I tried to breastfeed them. I also use a nipple shield. Had to almost completely bottle feed them for five days. I wasn't sure if it was because their gums were hurting. Or whether they liked the instant reward from the bottle. Or whether my supply was dropping. Or a mixture of all. I read a few tips of things to do with them to try and get them used to breastfeeding again. While doing skin to skin on Sunday night, he suddenly latched on and with no nipple shield. Since then we've done a few really good breast feeds. But sometimes he's still crying a lot and wanting the bottle instead. Starting to pump again to try and keep a supply/increase it. He was such an intense feeder for months that I had a big supply but he's been going longer between feeds and sleeping more at night so I think that's reduced my supply too. On this journey with you!
* He's also teething at the moment*