My 6 1/2 month old hasn't had a bowel movement in 5 days.?

She usually has at least one every 24hrs. She's been on breastmilk since birth, until recently; I gave her some cereal twice (which seemed to pass fine). Then, tried some food. The first night went well, but after that, she hasn't gone. I stopped feeding her solids, and she's just on BM for now. She won't take a bottle or a sippy cup to give her juices (I've tried several times), and I'd like to avoid a suppository if possible. When should I be worried? What else can I do?