I agree seeking out a pelvic floor PT or sexual health practitioner can be very helpful to confirm the pelvic floor dysfunction and vaginismus diagnosis, but to also evaluate and treat any other underlying problem that could also be impacting your pain. Hormonal changes can sometimes cause burning pain, as well as nerve sensitivity.
It is also my experience when my patients start to reach the larger sized dilators they will often feel a more intense burning discomfort or pain when stretching tight tense vaginal muscles. And that burning pain will linger, and not really resolve until they can insert even larger dilators. So for you, the #4 dilator in your set might not be pain free, until you are working with and inserting the #5 dilator.
You can also try using some local lidocaine cream to help with the burning with dilation. Lidocaine can be easily purchased over the counter or online at a strength up to 5%. Adding a little local numbing sensation to the entrance prior to dilation will help the burning and your fear of penetration.
