Yeast infection or Lactobacillus overgrowth?

I've been dealing with this issue for about 6 months now and I feel like I need a perspective from women who have dealt with this problem.
I noticed an intense itching around my labia which felt similar to dry skin. I tried using Epsom salt baths which would temporarily relieve the itch but it got to the point where I had scratched so much those just stung and irritated me more. The same itch is also around my anus now.
I have white discharge, which is thicker, or very thin watery discharge, but either way I find it ends up causing irritation.
I've been to the gyno twice and have been tested for STIs (all negative) and treated twice for what she assumed was a yeast infection. Once was over the counter and once was prescription. It felt like the symptoms got slightly better after the treatment but them came back again pretty quickly. It seems to be the worst right before my period.

I've very recently started taking a acidophilus supplement because I've heard that's good for yeast infections, but I'm worried it may make things worse if I have Lactobacillus.

I'm just really at a loss for what's wrong, it seems like no doctors have been able to tell me. Has anyone had a similar situation, and if so how did you treat it?
Thanks so much :)