Cricket, my first DS was born with a tongue-tie and I would say it's certainly a possibility that it is related. It is also worth noting that tongue-ties can cause other issues down the track too, such as speech difficulties and tooth decay (as the tongue can't clear food from the mouth properly), so there are other reasons also to consider having it snipped. It is a very quick and simple procedure.

I would also second the suggestion of a Lactation Consultant. That can really make a huge difference. In the meantime a nipple shield could be worth a try also.