What Causes Change In Taste Buds While On Treatment For Bronchitis?

My son, age 57, was sick for about a month, off medicine for the last 3 or 4 days, diagnosed with flu/bronchitis. He was taking predisone for about 16 days, albuterol for 2 weeks, and two rounds of antibiotics. For the about the last week his taste has changed, foods he previously liked does not taste good, sweets taste bitter. Also his hair has changed in that now he has to shampoo twice a day because of oiliness, and takes 2 to 3 shampoos to get the oil out, and then it feels crummy. Previously he shampooed once a day, and it was soft and manageable. What is causing the change in his taste and condition of hair? Thank you