Help! She all of a sudden won't take a bottle/cup!

[loveslucylee]

My lo is almost 9 months old and have been ebf since birth but I do work 20 hours a week and need to give her a bottle/cup of bm when I am working. She had trouble in the beginning (around 3 1/2 months) to taking the bottle, but did up till about 2 weeks ago and now won't take it. She shakes her head no and won't open up. She will go all day and then be starving when I get home. Have tried it in a different bottle and cup with no luck!
Any advice?