|Hi Julie, I don't know if this post will get to you in time, however, I would have to know more about what is going on. Are you treating your hand with the Technu and Ivy Dry?
First of all you may not have had poison ivy the first time you found blisters in between your fingers. To me your symptoms sound more like a different contact dermatitis, and because of the inflammation and tiny blisters it could be hand eczema. Also, with your history of sensitive skin the likelihood of this developing is higher. I found out that the tiny blisters I used to get as a child between my fingers and toes, and arches of my feet were actually a form of eczema! They could get very bad and they itched very much like poison ivy does. My Mother always assumed they were caused from sweating too much....but we were all wrong! I have not had anymore outbreaks since I was about 12. Please look up Hand Eczema on the web and see if the descriptions of symptoms match yours. Do not continue to dry out your skin as this will cause more problems and possible infection if you have fissures (cracks).
Another thing to point out, is that allergies of any kind can appear at any time of life. For example, for many years I used to wear Playtex living gloves (the kind they sell for dishwashing) to garden in as well as to protect my hands from household chores. About a year ago I developed an allergy to the gloves and got a VERY itchy rash on my hands and wrists. It took a long while to heal, as I kept wearing the gloves and unknowingly making it worse, as I had not had a problem wearing the gloves prior to the rashes. I switched to non-latex gloves but it wasn't much better. I now have to wear 100% cotton liners under the gloves. They have been a real lifesaver and prevent my hands from breaking out. They are called "Inspection Gloves", in case anyone reading this needs to buy some--they are impossible to find in stores but I finally found them on the web--on eBay to be exact. Expect your skin to change in some ways throughout your lifetime as this is a normal occurance.
Perhaps this is an allergic reaction to too many drying agents on your skin. I would stop using them if you still are. Cracked skin cannot heal on it's own. You need a good moisturizer like 100% pure shea butter. Keep us informed about your condition and don't forget to look up Hand eczema online just in case this could be your problem. Best of luck!