It's VERY unusual for a child to self wean at 10 months. According to kellymom.com, babies who self wean are usually 18-24 months old at least, are getting most of their nutrition from solids, and do so very GRADUALLY.
It could just be a nursing strike. Is there any chance your milk supply is low? Could you be pregnant? Sometimes during pregnancy the taste of the milk changes.
Keep offering the breast often. Make sure you're available to nurse whenever baby wants to. Try to avoid nursing according to a schedule for the next few days, just to make sure your supply doesn't totally dry up.