Wow, what a response, thanks all. Will work my way through the suggestions and questions.
I'm careful about wiping. Use flannel daily on nethers or shower. No worms. Have tried different powders and now use same one for years as none made any difference.
Lichen Sclerosis? Never heard of it. Will look that up, thanks. Steroid cream does help the itching, but it only treats the symptom not the cause. And can't be used more than 5 days at a time.
The dr I saw was at the sexual health clinic and specialised in dermatology of nether regions 
Tried sudocrem which helps with soreness and healing tears, but makes the itching worse. Not tried vagisil as loathe to put anything on it without a diagnosis, and also only treating symptoms.
I've seen proper psoriasis and it isn't that on my vag. No flaking skin, overgrowth of skin, or hardened dry bits. No shaving, just use trimmer to tame the hairy beast.
I don't use fabric conditioners. Try and use cotton underwear but no difference. I am overweight so there is some thigh rub, but thighs aren't sore or itchy, just the vulva. It is worse if I get sweaty though, and any moisture coming out of me irritates it.
Yes, antihistamines help with the itching but aren't a long term solution. I don't want to take them every day just because my fanny is making me want to rip my own skin off.
Yes, def worse at night, but then I'm probably more prone to feeling it when I'm in bed doing nothing else but trying to sleep.
I've tried the one dose fluconazole you can buy. Many times. No difference. And it is expensive.
My diaphragm gel is very acidic. It makes it no better or worse. Except it stings when I've got a sore patch of skin.
I've had many treatments for thrush over the years, but none work. Both OTC and gp prescribed. I thought it was thrush for a long time. I am in my 40s but I've had this since I was a teenager.
The hairy bit of skin is quite dry, hence the eczema suggestion by the dr, and recently I have tried oat based emollients and hydrocortisone cream. But it doesn't change the fact that it itches, and as soon as it gets wet it itches more. And the white toothpaste like discharge?
Re iron, I eat red meat and loads of green veg. No anaemia likely. Have annual bloods done and all good. Good diet all round really, though I do eat too much.
I can't give up chocolate! Rather give up sex!!!
From what I've read, vaginal dryness isn't dry skin on the vulva, it is lack of juices inside. Trust me, I don't have any problems there!! In fact, it is the juices that irritate it even more! My mid month discharge is a bitch for the itch.
Lots more votes for LS. I'm going to research.
Group B Strep? Never been tested. Had several vaginal births and no problems. Also had several courses of shit hot antibiotics in last few years for other health issues, and none worked on the vag. At least I cannot identify a definite timeframe to indicate they worked (but it has been fluctuating slightly better or worse over the years).
Wearing no underwear at night is worse than wearing something. No idea why. It feels like tiny biting ants are crawling all over my skin down there. Yuk.
I'll check out all the links now, thanks for sending.
Sorry to hear others are suffering too. It's pretty shit and annoying.