Ds is almost 4 and has always been fine about washing his hair. Until about 3 months ago when over night, for no apparent reason, he started freaking out completely.
He's fine for the wetting (which we do with a flannel) and shampoo, but rinsing it is impossible. I try to avoid washing it at this stage, just give it a bit of a rub with a wet flannel every few days, but sunscreen, and a sweaty hat head mean it needs to be cleaned properly once a week or so. We've tried face cloths over eyes, special spiderman goggles, youtube videos, a book, doing it himself, many different water vessels... He's still a sobbing, screaming wreck after I've pinned him down for dh to rinse him off. If he let me do it, it would take about 5 seconds 
Has anyone any amazing tips to minimise the trauma?