I've Had Random Bouts Of Sickness Over Maybe The Last

I've had random bouts of sickness over maybe the last year. Not sure what is causing it, which is primarily what my question is. Its come on on an empty stomach, after eating various different things. The symptoms I've noticed are listed as I feel them come on, and it comes on FAST: Nauseated, vomiting, diarrhea(occasional) PROFUSE sweating. Then as the nausea settles down a bit, the more long term symptoms are: Nausea, low temperature, sweating, restlessness, low heart rate/BP, possible vomiting if something exterior causes I (I.e, smells tastes, etc) No previous health problems, or allergies. Only Prescribed methadone to treat opiate dependency(MMT). Main concern is that its all a side effect from the methadone, being heart related. Have also been noticing others who attend the same clinic I attend experiencing the same thing, randomly, and exactly the same symptoms. Other concern is that it maybe is food poisoning of some sort from the water lines that they dispense our medication from maybe having bacteria in them? Not sure if that's even a possibility, but I'm reaching for answers, here! Haha. Tends only to last, at its peak, a couple hours. But the overall set of symptoms can take between 4-9 hours to be back to feeling stable and normal again. Obviously an appt. With my primary would be the first step for a possible EKG, but otherwise I'm unsure of what's causing it in the meantime.