The list reasons for changes in appetite is actually endless but I can give you key observations and suggestions. If she feels good otherwise you do not need to be worried but just watchful. Hand feeding is usually not a good idea at this age as she sees that as closer interaction with you and she might start to take advantage of that. Her growth rate is starting to slow down so her overall consumption could slow also. Many puppies that have been eating multiple meals per day will begin pick at meals sometimes or leave them out all together. She is also at an age where early hormone production can begin to cause slight fluctuations in behavior and appetite even though she is probably at least a month away from coming into heat. If you notice any other symptoms such as diarrhea, vomiting, coughing etc. let me or your vet know. You also mentioned that she is scooting. This can be a sign of anal gland impaction and or infection which will often affect appetite. Take a look at the article on "Scooting" for additional information.