Hm. Yup, your age shoots that theory of dryness.
Let’s see if we can narrow the clues down a little.

What other symptoms do you have? What made you suspect a Bartholin Cyst? Do you have a lump or swelling in the tissue? Any Itching?

Interesting that you get relief when you urinate. Did this sensation of burning begin after you started taking sitz baths? Or has it been there all along? I’m just curious, though soothing, if that could be irritating the vaginal area.

Another thing that can cause irritation is if you’re sexually active and sensitive to the lubricant or anti spermicide of condoms. I used a foam contraception eons ago, and had a similar reaction of irritation and burning. I can’t remember what my doctor told me to use now but it was a topical gel that helped calm things…and then switching the birth control methods.

We women are prone to a common, minor infection called vaginal vagosis. It can develop when too much of a specific bacteria grows in the vagina. And of course, the dreaded yeast infection but those tend to make themselves known pretty readily. Do you notice any unusual discharge?

If this persists you might have to visit your friendly gynecologist to find out for sure what’s going on. You don’t want put up with this for too long.
Have you had a pelvic exam?