Side Effect of Herceptin?

My friend recently completed chemotherapy treatments for breast cancer.  She also took the drug Herceptin.  Since her completion of treatment, she has experienced severe choking and coughing spells that come at no particular time or activity.  She feels something in her throat just before the attack and does cough up some phlegm.  The attacks are very severe, and anyone who is around when it happens worry that she is actually going to choke until she passes out.  The cough is very deep sounding.  She has been to an allergist, an ENT, and even a lung specialist.  They have done a CT scan, swallowing test, throat imaging, and lung tests.  None of the doctors seem to know what is causing her choking and coughing.  The lung specialist seems to think it is allergy related and increased her inhaler & allergy medication.  However, it doesn't seem to be helping very much.  Could this be side effects from taking Herceptin?    

[japdip]

Cough is one of the side effects of Herceptin but any of the side effects usually occur within 24 hours of administration of the drug. Some have been known to occur later though. This drug should be used with caution in persons who have previous lung disease.  I don't know if she is taking any medication for high blood pressure but many of these drugs do cause the symptoms you mention; just a thought. Can't really shed much light on the subject ... just keep looking I suppose.    Good Luck ....