I reckon a Diabetes 2 dentist must know what he's talking about. 'Wonder where I can find one?
So brushing hard is out, as advised by an number of contributors.
'Never heard of Oral Lichen Planus. However, I did some browsing and found :-
"Avoid spicy, acidic or salty foods if these make your mouth sore."
Sounds/feels familiar. My gums seem to have become sensitive to these over the last month or so. I ate an orange and an apple yesterday and my gums were stinging for hours. Same thing happens if I drink a beer now. I have recently had some extractions and have been using warm water and salt as a mouth wash. The extraction sites are on the right side, the sensitivity seems confined to the left, but if some of the salt gets over to the left, then I get a painful few hours. The gums (top and bottom) on the left feel rough to my tongue. A new dentist noticed some papules (little blister-like things) on the back of my tongue which seemed a bit larger than average. Pictures of these have been sent to the local dental hospital. Hmmmm!