On a whim I decided to take Jonathon in to the doctor's office today. His thumb is still swollen though he isn't crying over it anymore.
Two x-rays later and there you have it... it's fractured.
Yup, the little monster dropped a 12 pound bowling ball on his thumb and cracked the bone at the tip. The doctor offered to splint it, but Jonathon is babying it enough without a splint and anything we put on would get taken off in 10 seconds or less. She did say that kids heal really quickly from this sort of thing, so I think he'll be just fine. At preschool today they were practicing writing and he used his left hand OK so all should be well.
I'm sure when he's older he'll swear the bowling ball attacked him.