Hello Booboo, I am sorry to hear about your problems. In your position, I would drop the Yes VM and Sylk for now (especially as you say you are not dry) and just use a simple emollient on the vulva, such as Epaderm or Hydromol. You can also use these to wash with. I doubt if the fillers in Vagifem are causing a reaction, and as you used Ovestin for a while and it helped, that doesn't seem the likely culprit, although I don't discount the possibility. That aside, you might prefer the Estring as you can shove it up and leave it, and just use a little Ovestin on the labia once you feel better.
Do the labia look inflamed at all? Have you been swabbed for candida? Can I also ask how many Vagifem you are using per week? (Sorry, lots of questions.)
In the meantime, some find an ice pack between the legs, such as a tin of something that has been in the freezer (well wrapped of course!) can ease the burning temporarily.
JP x