Washing powder itch

[ohIdoliketobebesidethe]

We have finally concluded that the reason my dd1 (4yo) keeps itching like crazy is our washing powder. (We washed all the bedding yesterday and she had a terrible night of not being able to sleep - even when she climbed into our newly cleaned bed). We're feeling pretty guilty as it's been going on for ages. We've been to see the GP 3 times and even a dermatologist. She's been plastered in creams and the whole family has been treated repeatedly with worm medicine - it seemed to work sometimes too.
We use Ariel non-bio and usually use sensitive conditioner but didn't use any this weekend.

Can anyone who has been through this before tell me whether we just have to keep swapping and trying new brands or whether there is a really gentle product we can switch straight to to save the hassle?

We use filetti, its the only one that seems to be v. mild (non-bio, no perfume etc etc) has been recommnended by various dermos and also have a think about getting a water softener as you'll use less as well

That's really helpful thanks - I hadn't even thought about water softener.
Do you think the conditioner makes a difference?

we don't use it - i can't get away from the idea that something that smell strong or coats the fibres is good for your skin

have a look in the allergy section, been discussed quite a bit.