I agree with Caryopteris.
Abrasions can easily be caused through masturbation in both men and women. Vagisil will help, as will any other recommended anti-septic creams. Also vaseline will help to keep the area from getting dry and cracking.
The burning sensation you feel on the labia whilst urinating is likely to be traces of urine entering the cut, and as there is a high acidity content in urine, it causes the cut to sting, much like getting a paper cut on the finger and dipping into a bowl of vinegar.
I wouldnt worry about this. Do you have long nails? Maybe this was the mid-masturbation culprit. Either way, I would not stop masturbating - but try to steer clear of that particular part of your labia.
Hope this helps
A
I think it's a little abrasion. You could put some aloe vera on it or some Vagisil or Lotrimin cream or Neosporin cream with the anesthetic in it. I would think any of those would feel soothing. You just have to be careful. Sometimes the vaginal flora isn't perfect or for other reasons the viscosity of the natural lubrication isn't enough. Then you can get a little abrasion. It's helpful to pay careful attention to any dryness or have a lubricant on hand. Supposedly olive oil is okay per my gynecologist. I've used 100% aloe vera. If it's not pure aloe vera it can burn.
at about your age, i had a guy feeling me up,
afterwards,
i went to loo and man was the pain excuciating!!!!
stung like mad,
didnt know why,
obviously now i am older i realise he was too rough!
but pain went after a few days.
think he just rubbed tooo hard?
have had no pain/problems after a few days of healing.
hope this helps