What Causes Cough And Shortness Of Breath After Swallowing Saliva?

suddenly I could swallow saliva which fallow cough and short of breathing for long time and i almost feel that I am on the verge of collapsing. my heart ECG is normal. earlier it used to occur while sleeping which is diagnosed as sleep apnea . but now while fully awake and while doing normal work it happened. all this started at my age of 50 and now I am 60 female. I have hyper tenssion and diabetic