Sudden almost bald spot in front of head on hairline? (Photos)

I woke up yesterday and noticed a bald spot right on my center part at the hairline. It just seemed to have suddenly appeared out of nowhere. It's not fully bald but the hairs that are there are very fine and very short. What could this be caused by to just suddenly appear? It's not very circular and not completely bare so I don't suspect alopecia? I'm traveling in SE Asia with my husband at the moment. Any insight would be greatly appreciated.