Overtired baby

My baby was a great napper until 6 week leap. Then was great again for about 4 days. Past three days he has been fighting taking naps. Yesterday only slept three segments of 30 minutes for a nap. WHY. And he is SUCH a light sleeper too. He used to be able to sleep through anything. I always offer a nap about hour and a half after a he’s been awake and has sleepy signs, he is just fighting the sleep! BOUT TO LOSE IT UP IN HERE