My 8months old baby having a running nose with light fever for 3days, she's taking calpol paracetamol and antihistamine, but she still sick.

Child with fever. These sort of symptoms can range from a simple cold, to an ear infection or other type of infection. With a child that young, with a fever over 100.5 I would recommend evaluation by a physician. .
Most likely allergy. Mild illness in infant with history of allergies. Most likely allergic rhinitis. Stop calpol paracetamol,continue antihistamine. Acetominophen Ok if temp goes higher, bu if that happens should contact health care provider. Also evaluate for allergen exposure, feather pillows, new shampoo, new meds, etc.