You don t state how long you have been wheezing and whether you have had any attacks like this before. I m assuming his is the first time it has happened. Also, are you coughing anything up? Do you have a fever? It sounds like you have taken a lot of your nebuliser and this could be causing your heart rate to be elevated. It is one of the side-effects of this group of drugs called bronchodilators. The most likely cause is that you have asthma and need to be on regular inhalers. You may also have a chest infection if you are coughing stuff up and have a fever. The other causes of wheezing may be an allergic reaction to something in your environment such as a cat or dog. Could you have inhaled a foreign body such as a piece of food or bone. Alternatively, some people can spontaneously develop a small collapse of a lung called a pneumothorax. This can cause shortness of breath and wheezing and is of sudden onset. A chest X-ray may help confirm the diagnosis.