A nurse is working at a family health care clinic and is speaking with the parents of a 7 year-old boy with phenylketonuria (PKU). Their son has had mild cognitive impairment as a result of the condition and has been screaming and headbanging several times a day. The parents express that they are "at the end of their rope" and "don't know what else to do." Which of the following is the best response for the nurse to make?