I do - allergic eczema. I'm especially allergic to a chemical family - Methylisothiazolinone (MI/MIT) & Methylchloroisothiazolinone (MCI) used as preservatives in a great many liquid soaps, shampoos, and household products. This is, apparently, a fairly common undiagnosed allergy and caused me years of misery before an allergy test identified it.
Key for me is, of course, avoidance of allergens. If you can find out exactly what you might be sensitive too, it could make a world of difference. I found some bath products that work for me - Aveeno Sensitive Skin and Frizz Ease Shampoo don't have MI/MIT/MCI. They cost more than I'd like to spend, but are worth it to me because I know they don't irritate my skin and I like the way my hair looks and feels.
According to my dermatologist, one of the most effective treatments can be both natural and free - UV light therapy... The simplest form of light therapy (phototherapy) involves exposing your skin to controlled amounts of natural sunlight. The theory is that vitamin D helps. You want to get sun but no more than a "sun-kissed" mild pink. DON'T get sunburned - that's bad. Be cognizant of the long-term risks of sun exposure, but controlled doses can be safe and effective. I get UV-B light therapy 2x/week in a doctor's office but I'd be doing natural sunlight if the UV-B wasn't a free option for me.
Other inexpensive alternatives are bleach baths (
http://www.mayoclinic.org/diseases-conditions/eczema/expert-answers/eczema-bleach-bath/faq-20058413) or apple cider vinegar baths (about 2 cups to a tub). Plenty of people with and without eczema swear by apple cider vinegar as a natural option for all of their bathing and hair care needs.
I hope others might have some great solutions for you. Good luck!