Internal mouth blisters

I often get a type of internal mouth blister that occur in all places inside of the mouth.  They are relieved when I simply scrape them off.  My mother used to say she would get these if she ate oranges.  Lately, it seems like I've been getting these blisters a lot more often than I used to get them.  I am very careful of what I eat, since I learned I had so many food sensitivities and allergies that are clearly linked to GERD and IBS with constipation.  So, I already know about many of the food issues, including the obvious gluten and lactose intolerances associated with the IBS (with constipation).  I've gotten these blisters for many years, but I am concerned that I am getting them more often than I ever did in the past.  And, recently something much different has happened to me.  A large section of skin from inside of my cheek simply melted away and peeled off when I had some of these blisters cluster together.  This happened twice close together and quite recently.  Then, just yesterday I had one of these blisters on that same section of my cheek where the skin melted away.  It wasn't clear like they usually are.  It was clear, but it had red spots on the top of it that I'm assuming are because the skin hadn't completely healed in that area inside of my mouth.  I've asked both conventional and natural doctors about this.  It seems like no one has any real answers for me about this problem that seems to only be getting worse.