Gum infection leading to tooth extractions

I wonder if anyone else has experienced this?

In the last year I have had three very painful infections deep down in my gums which have resulted in my teeth being extracted - the third extraction is next week! X-rays show the extent of the infection and how it has destroyed the tooth above it.

I have regular checkups, clean my teeth at least twice a day with an electric toothbrush and floss most nights. My dentist always praises me for my dental hygiene and has not needed to refer me to the hygienist for a deep clean.

At my last visit, she suggested that I get my blood sugars checked as diabetics can get frequent infections. This has now been done and they are fine, not even near the pre diabetic level. Both the dentists I have seen at the practice are bemused and cannot explain why I get these infections, in my lower jaw but at both sides. I will soon have lost three molars so eating is going to be challenging until I can have implants or dentures - six months after the extraction!

At this rate, I will lose all my teeth before long if I cannot get to the root (ha ha!) of the problem. I go to an NHS dentist and am considering going private to get another opinion but I am not sure if it will make a difference.

Any suggestions as to what is happening or what I can do. I am 62 if that makes a difference.