What would cause sudden severe upper left side abdominal pain w/chest tightness, SOB, & faintness found to be moderately relieved by inhaler?

You're asthmatic? presumably it could be many things. This combination sounds serious (especially the SOB and faintness) so if it happens often or lasts long you should be evaluated for things like blood clots. OTOH, if it has only happened once or is always very short lived it could be either mucus trapping, gas trapping (in the intestine) or "pleurisy" which just means pain coming from the lining of the lungs.