Hello & welcome, I am Dr. B, a licensed veterinarian and I would like to help you today.
Do you mean she isn't passing urine or feces or both? Any straining to do either?
Any gagging, retching, lip licking, drooling or vomiting?
Is she drinking even if not eating?
Are her gums pink or pale/white? Moist or sticky?
If you press on her belly, any discomfort, tenderness, or tensing?
Could she have eaten something she should not have (ie bones, toys, plants, chemicals, etc)?