Hyperventilation

I've suffered from episodes of it in the past but yesterday i had an especially severe one to the point that i thought i was having a heart attack (i had crushing chest pains, shortness of breath and was on the verge of blacking out) and had to call 999. Suffice to say i was ok. Have had pretty bad sinusitis in the last week and am just back at work after 3 weeks of a flu like bug so i suppose these could be partly to blame. Has anyone had similar experiences?