1 year old stumbling

My son woke up this morning normal and he ate his breakfast and began to play. Hes been walking for a while and out of nowhere he started stumbling. The best way I could describe it is when you're wearing high heels and don't know how to walk in them. He then started walking normal but after I changed his diaper he started stumbling again. He doesn't seem like he's in pain but right now he is just standing in one spot looking at a book. I usually wouldn't be concerned but this is out of the ordinary and he never stumbles.