Hi there, Have you considered acid reflux, or GERD? A metallic taste is not typical, patients with reflux tend to complain of more of a bitter or sour taste, but the pattern of your symptoms suggests that it could be a possibility. When you exert yourself, there is increased pressure on your abdomen, which makes it more likely for acidic stomach contents to be pushed up. It is likely that you already have an underlying acid reflux problem, but it is aggravated by the exercise. Yes, many people with acid reflux also feel breathless during an episode, even though the lungs are completely unaffected. The cough is also explained, because acid reflux triggers it in two ways: firstly it irritates the nerves that are along the oesophagus, which causes a fake cough. And once it reaches the throat, the acid can cause an actual cough by irritating the airways. I would recommend that you try some medication to reduce your acid, called proton pump inhibitors like omeprazole for at least two weeks and see how you feel. Try not to have a big meal before your exercise, and cut down on things like caffeine and alcohol, or spicy and acidic food. Hope this helps, and all the best to you. Regards, Dr. Teh