Sudden change in beahaviour Labrador

Sorry if this a bit long but Im lost and worried. Our 8 month labrador has had 2 very sudden changes in her behaviour since Monday. Firstly she wont eat the usual dog food shes given. Its fairly similar to what shes been getting since we got her at 7 weeks. I put in a hot dog sausage into the food and she ate the hot dog but left the dog food. Up to the weekend whenever her food was being made shed be bouncing round the place waiting to eat, now shes not the least bit intersted. Im thinking this might easily be sorted by change of food.

The second issue is somthing were baffled by and a little worried by. Her behaviour when in our kitchen our bedroom seems like shes aggitated in a way and we think its shadows on the floors and walls. She wont stop barking, yelping and squealing and keeps walking around the kitchen. She usually lies down when were in the kitchen or is under the table looking for food and when we go to the bedroom to use computer or watch shed usually lie under the desk or bed. Now she wanders aimlessly around the bedroom and landing. Would really appreciate if anyone has any advice or has had similar situations especially the second issue.