I would say your problem could be caused by yeast infection, taking too many antibiotics, your pH balance is off, could be allergens. I would recommend seeing a Gynecologist, ask them to test you also for diabetes; you could have a parasite too. Yes, soaps, shower gels could cause it, you can experience itchiness down there, swelling, yes it will burn because you've got inflammation down there too. Always wear cotton underwear, really silk underwear and thongs can be bad for you and also watch what you're washing your clothes in too. Also, tight clothing is bad and can make it worse.