I've had one or two over the years, mainly when I was a child and relatively few as an adult - not enough to identify any trigger but the are the most miserable thing, you have my sympathy. My OH is certainly a lot better but it can be frustrating with the clothes, we end up ordering expensive t-shirts from the states as these are the only ones that he is sure he can wear. Everything else is a hit or miss. We use Surcare washing powder - the only completely unperfumed one I have found and he uses just basic bars of soap for washing, being a man he does his hair with that as well as it is cropped short. I think that simple may do something suitable but he finds liquids not as good as solids so the shower gel is not to bad, but the bars of soap are better. As I say, no idea if this will help, but maybe something else to track in your diary. e.g. used whatever body products, wore whatever clothes etc.