Help getting baby to open mouth to latch

I need some help...My little guy used to open up wide, but wouldn't latch so we started using a nipple shield at 3 days old at the suggestion of a lactation consultant in the hospital. I'd like to stop using the shield but he won't open wide enough.  He'll only open up a little and start sucking.  I think he's used to the nipple shield being able to just slip in without him having to open up really wide. He’s getting a lot more milk without the shield but it’s extremely painful and causing nipple Vasospasm I’m so sad and afraid I might not be able to continue exclusively breastfeeding 😭Any thoughts on how to get him to open wide? I try expressing some milk and tickling his upper lip/ nose but no luck. Any advice would be appreciated!