I do not have IBS-D, (and my IBS-C is history) but I do have issues with dry skin, and my wife has even more dry skin issues. Winter (in Minnesota) increases the challenge, and I assume that diarhea, with it's dehydrating tendency would certainly add to it. Also, if you limit your dietary oils and fats (which many IBS'rs do), that doesn't help the situation either.
I know exactly what you mean. I've had IBS for 17yrs (I'm 27) and I have horrible eczema. My skin is sooo sensitive. I have to use free and clear detergent, Dove only for my showers, no fabric softners or dryer sheets or my skin gets worse. I use Eucerin. It helps but it burns when applying it if your skin is slicing.