Do not google it!! I did this once with itchy skin and no rash/no obvious cause and frightened myself half to death with all sorts of crazy possibilities, mostly about rare liver problems. Went away and I was fine, never found out the problem. Honestly, the most logical reason is that it is nothing significant at all, some minor irritant that is not severe enough to rash but enough to itch. A medicated talc could help soothe the skin, or a warm bath with a little olive oil in to moisturize and soothe.
If it is still there tomorrow and you are worrying, go see a GP and they might run a few tests just to check there is no serious underlying cause.