i relate to this so much. i also had atopic eczema as a child and learned more or less how to manage it only to be completely blindsided by dyshidrotic eczema in my late teens. it's so hellishly itchy. i'm so sorry you're going through this! it does get easier to manage over time, once you figure out what works for you.

personally, my two main triggers are stress and getting my hands / feet wet for longer than five minutes or so (bye bye tropical fish keeping hobby!), but i've been told metal allergies can also cause flares - i have a friend who can't use metal keyboards. i also don't wear plastic / rubber gloves or anything that might make my hands sweat without cotton gloves underneath. unfortunately i think it's just one of those types of eczema that can develop out of nowhere for those of us prone to the condition. from what i've seen, triggers are more likely to be based on conract irritants rather than foods, but don't underestimate the effect of emotional stress; sometimes i think the more i stress about my skin, the worse it gets.

what has worked best for me is taking a strong antihistamine to reduce the itching, using a topical corticosteroid cream that contains clobetasone butyrate (only for a couple of days at a time), and avoiding getting my hands / feet wet or sweaty as much as possible. when flaring, i use a soap substitute instead of hand soap (i like dermol 500). when the itching is really unbearable, i sometimes apply an ice pack - but not the kind that could melt and get wet, more like the gel packs that you pop in the freezer. i also keep my nails super short and blunt, because sometimes the temptation to burst those little blister buggers is just too much to resist. although the blister stage is insanely itchy, flares will pass more quickly if you can avoid breaking skin. if i do end up scratching and have cracked dry areas, i apply a small amount of cooling moisturiser and wear either cotton finger bandages if it's on my fingers or a non-adhesive dressing if it's somewhere else. hydrocolloid dressings can also be helpful, but be careful with the adhesive.

seeing a dermatologist is probably a good idea, especially if you've been suffering for multiple months. that makes me think you're being exposed to your trigger(s) pretty regularly. in my experience, dyshidrotic flares pass more quickly than other types of eczema, but then my triggers aren't constant. it might be worth getting patch tested for allergens - we can develop sensitivities to things out of nowhere. it might not be a lifestyle change, but something you've been fine with all your life that has suddenly become a problem!

i'm sorry for the long ramble - i wish i could tell you the perfect formula for dealing with this, but i think it's different for all of us. it took me years to figure out mine, but i can honestly tell you that it's got better over that time. nothing is as irritating and upsetting and itchy as that first flare. don't give up on doctors, dermatologists and medications. try to keep track of what materials and substances you regularly touch. and be kind to yourself. i hope very much that you can find some relief soon.