@donasmrs-- I think that "unexplained itchiness" refers to itching where the cause could not be identified.
There can actually be various causes of itching. Many people think that it only occurs due to allergies but that's not the case. It can be due to allergies, it can be a side effect of a medication, the immune system may cause it or it can even be psychological. I have heard that it's possible to itch because of anxiety or nervousness.
Sometimes the cause can be found easily, other times, the cause may be unknown. It's not always important to know the cause. I mean, if it's temporary and if treatments like lotions and medications work, then it's not necessary to know exactly what caused it. But if it happens all the time, then it's probably an allergic reaction to an allergen and that allergen needs to be identified and avoided as soon as possible.