My 7 Year Old Granddaughter, With Chromosome 18 Distal Q

My 7 year old granddaughter, with Chromosome 18 distal q deletion, missing genes 20-23, is now taking Risperdal for bipolar-like behaviors. Her morning dose is 0.25 mg. Last week, her evening dose was increased to 0.5 mg. Within the last two days, she has developed a rash on her face and neck. Her skin feels extremely dry, and is covered with very tiny bumps. Could this be skin condition be related to the increased dosage? She weights only 42 pounds.