I wouldn't take the antibiotic, as you need to know what you are treating and if there is an infection it may be resistant to that one anyway.
A lot of my burning has been found to be an undetected UTI, that has been rumbling away since I had minor gynae surgery 20 months ago, three specialists and lots of ££££s later but I am about. 75% better over all I have had to have six weeks of antibs, changing to a different one every two weeks, I am on my last lot now.
I am on ami also, the burning is still there but greatly reduced as the UTI has irritated the Pudendal Nerve. The least invasive investigations you have the better, as those nerves are already on red alert.
I have seen an amazing Vulva specialist, and she spent 40 mins thoroughly examining me in and out, so gentle and caring, did the gynae do the cotton bud test for vuvlvodynia?
I smother myself in the yes "oil" twice a day down there or more if needed stops any irritation from urine etc, also Sitz baths can make it worse, I use dermol 500 as a wash as just water is very drying but other things cause irritation.
If you are uk based I can pm you the name of the lady I saw, she takes more in depth swabs than the usual and mine was spot on including my PH level.
Vaginal burning is the pits...........if it's VA then the estring I guess is your next stop, I can't use vagifem or Ovestin either make me burn more.