For topical treatment... water with Apple Cider Vinegar ( very diluted) in a spray bottle or peri bottle. This will help restore normal ph.
Garlic suppository is effective for yeast but a warning- it wreaks! LOL ( It doesn't really sound like you have a yeast issue) Eat LOTS of it as well.
For external burning... topical PLAIN whole milk yogurt is soothing but messy. Wear some sort of barrier like a pad and plan to not leave the house
BEST most effective natural antibiotic option available for ANY infection... Colloidal Silver. Find it at your local heath food store. I've seen this stuff treat an incredible variety of infections in my own family as well as many of my friends and their children. It is absolutley safe in pregnancy. If you do go ahead and use silver for anything, make sure to be faithful to some sort of probiotic as while silver destroys bad bacteria, the good suffers as well. An easy probiotic to take daily is plain kefier since it's drinkable and quick. Easy to find at regular grocery stores these days too. Plain yogurt is a great option too. I'd stick with real food over supplement versions of probiotics. Taking in a probiotic daily is a great idea anyway to promote healthy flora to combat yeasties and digestive issues etc.
Don't panic or give in to alarmism about these kinds of things. Go with your instinct. If it were me ( and it has been before) I would try all possible at home options while not ignoring anything severe. Hugs mama!
ETA 2 more topical ideas for an antifungal - you can apply silver directly to your yoni as well as ingesting it. Also, maybe 1 or 2 drops of Tea Tree Oil diluted with evoo. Make sure it's very diluted as straight tto will burn skin.