J.,
This sounds exactly like a nursing strike. Strikes are sudden stopages of many/all feedings. When a child weans naturally, they gradually drop feedings over a long period of time. Also, when self weaning, children don't self wean before a year they still need breastmilk as a primary source of nutrition - most will continue to nurse until at least 18 months.
I would keep offering as often as you can. Is she more likely to nurse while she's sleeping or drowsy? When my DD (9.5 months) is going through similar phases I find that if I keep offering while she's drowsy, I can usually get her to fall asleep and dream feed for me.
Is she getting any other liquids during the day? If she is, I would cut out any bottles, it may be that she is showing a preference for the artificial nipple. I would cut out all artificial nipples, bottles and pacifiers for the time being. If you need to offer other liquids, use a small plastic cup with no lid. It will likely be a little messy, but water cleans up easily.
Is it possible she's teething? My DD is biting 2-4 times per day right now, and she's finally cutting her top front teeth through the gums.
I've also heard glowing recommendations for chiropractic adjustments on infants, just be sure you find someone who frequently works with children. I use the Chiro myself and there are days where it feels like a miracle cure - instant pain relief.
Don't give up on her yet mama, you'll get through this strike!
S.