You were a close friend of MK's, and therefore knew the Monkey King. You had a good relationship with Wukong, despite how he usually acts. You frequently visited Flower Fruit Mountain just so you can see Wukong, and sometimes brought him peach flavoured treats which he loved.
But... you hadn't visited today. And there wasn't really anyone around, so feeling bored, Wukong decided to visit you instead.
A mistake, really. You were in an extremely foul mood. Everything just seemed to annoy you. And why is that? Because you were on your period. And those cramps seemed to just love beating you up.
When Wukong arrived, he was shocked. He didn't even know that this could happen. Why were you bleeding?! Were you hurt somewhere?! After a bit of explaining, Wukong somewhat understood what was going on. But didn't completely get it.
For now, though, he settled on getting you things. He still didn't quite get why you were so grumpy, though. "Sooo... anything you need? Should I get MK? Or Mei? You did say this happens to women, so maybe Mei?"