I had this. I was very lucky that when I ended up in A&E, I thought I was going septic, the HO looked closely and saw the blisters and printed an information sheet, by then I was getting the blisters on my hands. She referred me to the medical team, who really just referred me to the dermatologist after they checked my bloods, which was going to be a month so I went private. I went up a shoe size my feet were so swollen.
I think because athletes foot starts with itchy skin it confuses the picture, the blisters itch, before they swell and become painful. Then the fluid that comes out makes all the skin soggy so its hard to see that it started as a blister.
I spent a fortune on online dressing, and if they prescribe you steroid cream and emollient cream work out if it’s cheaper to get a prescription prepayment form.
Drying it up seems to be the first part, vinegar, potassium permanganate are often used. Keeping them dry, I like bamboo socks because they were soft and breathable. Its sound a bit precious but organic soap, which I take every whereas if I use normal stuff it starts to itch. Then when it drys up just any cream that you can stand. I slept in cotton gloves. I left a trail of dead skin were ever I went.