Interesting that you complain of stomach cramps - gut maybe? The GI tract is connected to the heart via the vagus nerve. It's not unusual for a GI problem to trigger tachycardia. I had to get my heart reset in the ER during a 5-hour episode at 168 with irregularities a few weeks ago.
Usually my tach is triggered by a food intolerance. I found the problem after I went to an allergist who had me keeping a food log for a few months (with my reactions recorded 1 and 2 hours after eating). When I got a whole long list of seemingly unrelated individual food triggers I looked them up on the internet with "food allergies" (or intolerances) and found they all had one thing in common - sulfite.
I'm not saying you have the same thing, because there are plenty of other causes and plenty of other intolerances if it does happen to turn out you have a food sensitivity. It's just worthwhile to keep a log of your eating, drinking, and your meds, and reactions - to help your doctors rule out something like allergies and intolerances.
Meantime, look up Valsalva Maneuver to stop the tach. You hold your breath and push like a bowel movement for half a minute or so. If that doesn't work, try a few good coughs. They should have told you some tricks like that in the ER. I saw my cardiologist too, and he gave me a few inderal pills to try. I had another episode last night after drinking a tiny glass of wine. (I knew better too, and I did try the Valsalva.) It took about 2 hours to work, but no ER.