My Mother (94) suffers from Asthma, and currently has cough with phlegm?

Her breathing is very bad and the phlegme blocks her tubes when she coughs. According to the Nurse and Doctor it is not a chest infection. She has a problem with any movement i.e. getting up on her feet, sitting down, and walking because her breathing is so bad, she is OK when just sitting down apart from when she coughs. It seems to be a new type of cough as several people we know seem to have it, but it does not seem to be infectious. No-one has experienced a cough of this type before, I can't help but wonder if the volcanic ash has anything to do with it, but may be my imagination is carrying it a bit far. But it must be something different in the air.