My Mother, Age 86, Has COPD Which Is Being Controlled

My mother, age 86, has COPD which is being controlled with meds and inhalers. For the past several weeks she has a very deep cough with a lot of mucus. I wanted to take her to the doctor, however, she has an appointment on Wednesday and says she will wait. She says she doesn't feel sick, however, she never tells the truth about these things. Do I have anything to worry about?