His time of the month..

Is it possible for a 7 year old boy to be experiencing PMS? Because all weekend, my son has been such a grump. He went to 2 birthday parties, got a brand new webkin, and some pokemon cards, yet all he's done is whine and complain about anything and everything. I tried getting him out of his funk by making plans for his own birthday party coming in about a month, but he wouldn't have it. It just depressed him to talk about his own birthday, when the party he went to yesterday had no goodie bags. Good lord. I hope he gets his period soon, or just gets over all the injustices he feels that has been bestowed upon him.