Please stop giving her Xyzal (levocetirizine) and contact her pediatrician right away. This medication is generally not recommended for infants under six months of age. Antihistamines like levocetirizine can cause drowsiness and decreased activity in babies, which likely explains why she has been less active. For her eczema, it is safest to consult her doctor for infant-safe treatments like gentle, fragrance-free moisturizers. Please have her evaluated by her pediatrician to ensure she is safe and to find a gentler way to soothe her skin.