My Dad Was Prescribed This Medication After Being Discharged From

My dad was prescribed this medication after being discharged from the hospital yesterday along with another medication which is amox-clav 875. His tongue has white blisters on it which feel like sand paper and everything he drinks like water or soda, everything he tried to eat even a piece of light bread sets his mouth on fire and his tongue is blood red. Is this a concern or an allergic reaction to one or both medications?