My 5 months and it's a boxer and for the past day she will walk slowly and cry for no reason and be very lazy

More details please?

Is she eating? Drinking? Any vomit, diarrhea?
Did she get into anything?

How long have you had her? Has there been any recent changes in your family? Does she walk around whining and seem anxious? Or does she lay in darker corners and whine in a way that would almost seem uncomfortable? More details would be helpful.. :)