thanks for writing to HCM,
firstly i would like to advice you not to stop the Parkinson's disease medication without your doctors advice.
For her present problem, i'll advice her to inhale steam for 10 mins 3 times a day. firstly as soon as she get up in the morning before eating anything, one time in the day and one time before go to sleep. As soon as her sputum tends to loosen up, cough
out as much as possible.
Also she should start doing some breathing exercises- like deep breathing exercises, huffing and coughing, chest expansion exercises.
A physiotherapist can help her in all these exercises as well as in chest clearance.
If all of this still doesn't help take the help of her exiting medical practitioner who is treating her for parkinsons. Kindly do not delay a prompt action.
i hope this helps
wish her good health