I had the same problem with my third. It sounds kind of crazy, but I developed an allergy to both the laundry detergent I was using (the Arm & Hammer brand) and the toilet paper I was using (Angel Soft). The good news is that switching brands helped a lot. The bad news is that the allergies have stayed with me. After switching brands, it took a few days for the symptoms to disappear, but I felt so much better when they did. At the time, we thought it could have been one or the other, but when I tried one and not the other (like using the Angel Soft but not the Arm & Hammer and vice versa), the reaction would return. You might very well have developed an allergy to something, too, and it could take some playing around to figure out exactly what it is.