I don't know.  Send along some photos and x-ray images.

I'm just a dental student so I don't know a whole lot yet, but I recently
read some information about the effects of saliva on oral health.  The
information I was reading was based on studies of people 65 years of age and
older, but I thought I'd bring it up just in case.

I learned that a decreased amount of saliva can lead to an oral environment
that is more susceptible to tooth decay.  One of the greatest causes of lack
of saliva (dry mouth, or xerostomia) is medication side effects. With aging
often comes health conditions that may require medication.  Medications that
treat high blood pressure, allergies, depression, and sleep aids can lead to
a decreased amount of saliva.

So my question is, have you experienced dry mouth recently?  Did you start
any new regular medications within the last few years that may have dry
mouth side effects?

Again, I just recently acquired this information so I'm not sure of all the
real-world applications.  Hopefully some of the experienced dentists here
can verify or make any needed corrections/additions.  My goal for presenting
this information was to try to help you at least narrow down the causes.

--Stephen D

    A sudden increase in caries incidence with a new dentist certainly is
suggestive.
    OTOH, I have several patients who have had what look like early carious
lesions (cavities) on x-rays that I do not fill because they have shown
no apparent change over several years.  Of course I will be more
conservative if I know the patient is in regularly for checkups.  With a
new patient I have no way of knowing this, and might be more inclined to
restore doubtful lesions.

Steve