I'm allergic to a lot of creams and lotions, including hydrocortisone. I haven't yet been able to figure out if it's a particular ingredient of class of ingredients since there doesn't seem to be a lot of overlap in the ones I'm allergic to.
FYI, Target has cheap store brand antifungal creams. Terbinafine, Tolnaftate, or Clotrimazole. Terbinafine used to work best for me, but now I seem to have developed an allergy to it. Clotrimazole never worked, but Tolnaftate seemed to work this time.
I've had allergy tests for food and seasonal allergies, and they told me I was allergic to almost everything, including some things that I'm not allergic to at all (like eggs). I'd say it has only limited value.
Diet is definitely a factor in my skin problems, but I haven't been able to figure out any specific substance yet. I tried a gluten free diet for a few days, and as a result I learned that I'm probably allergic to beef! I ate almost nothing but beef and cheese for those few days, and I woke up one night itchy all over and it was slightly difficult to breathe. As long as I have it only occasionally I'm fine, though, maybe a little itchy.
I switched to bar soap, and that seems to help. I try to only use powdered laundry detergent since it rinses out better and has fewer chemicals than liquid. I need to find shampoo with fewer chemicals, and I should switch my hand soap to bar soap when I run out.
Aveeno lotion works best for me. I'm allergic to many of the others dermatologists have recommended, such as cetaphil (maybe it's the almond oil) and Eucerin. Or if it's not an allergy, it makes my eczema worse.
There's some evidence (you can look up studies in the medical literature) that taking probiotics as a child helps reduce the risk of eczema. As an adult they didn't seem to do anything for me, and maybe made it slightly worse. I don't think any studies have been able to show a benefit for adults yet. You can make your own probiotic yogurt if there's a particular strain you like. Just dissolve the contents of one capsule in cooked milk (basically heat to 180F then cool to 100F to pasteurize it again) and leave in a warm place overnight, like making yogurt. Try this at your own risk, of course.
There's a company that makes probiotics for your skin.
https://www.aobiome.com/ Maybe worth a try. They say that surfactants/detergents kill the bacteria, so you have to be careful if you use it not to render it ineffective. Apparently you can get the same bacteria by rolling around in the dirt, as long as you don't mind being dirty.