You sound very uncomfortable....3 days and I'd be asking for help....not 4 months.
Some recommendations:
#1 - take a bath with both salt and white vinegar or apple cider vinegar. About 1 C each. The salt is naturally anti-bacterial and the vinegar normalizes the Ph in your vagina.
#2 - start taking PRO-biotics. Available just about everywhere now. Or eating organic yogurts. Or both.
#3 - start ingesting Apple Cider Vinegar...in your salads, on an avocado - daily, diluted in water
#4 - have you tried an OTC yeast cream like Monistat? If so, what were the results? Did it help?
#5 - If the cream did not help, you can also try regular diaper ointments, like A&D, Desitin, etc.
Wear only cotton underwear and only loose fitting pants or skirts. No tight jeans, no thongs until your itching and burning is relieved.
And if you do respond positively to the Monistat creams / inserts, it's quite possible you have infected your underwear over this amount of time, and even if you clear up, you can reinfect yourself with the same underwear. And there is no killing a fungus in underwear. Throw it away and buy new. Sorry...but you're worth it.
And - no soap. Do not use any soap on your private parts until this is cleared up. And take some Motrin or Alleve to help reduce the swelling, but only for 3 days.