Hi Nailit I am in the same position as yourself and it can be upsetting when your breathing gets that bad. One thing worried me , you said you used your nebuliser every half hour , that sounds a lot , on bad days I use mine maybe 4 times a day . I had a time when my heart would be racing and I would get breathless and I would use my nebuliser and it was not till later when I was in hospital that a Dr said to me "you realise that the nebuliser makes you heart race " and of course that can make you feel worse . I am not very good at calling an ambulance I hang on till I really need to get one, usually end up calling one in the middle of the night much to my daughters disgust lol. I now have oxygen at home which has lessened the need for hospital visits. Please don't hold out phoning for help if you need it .