I had similar side effects to drinking (before i stopped totally) which was related to liver functioning. I dont have any blood pressure or dietary problems but for some reason my body didnt agree with alcohol, and it was only certain times. Turns out my liver isnt the strongest. When you're stressed your biliruben count increases, which makes processing normal toxins, like alcohol, in the liver more difficult. So, when stressed, or having been for that week, alcohol wasnt processed as well by my liver and the side effects were greater chance of racing heart, sweating etc, just like drinking a heap, but caused by a little amount.
If you have sleep apnea, alcohol can make it worse. When one stops breathing due to apnea and the lungs are not taking in oxygen, the heart tries to compensate and pumps harder. If the event lasts long, the body ends up in extreme stress with an adrenaline response, which can be mistaken for a panic attack or anxiety.
It may be that the alcohol has brought to your attention a medical condition you might otherwise not have been aware of till it had done some damage. A sleep study would be at the top my "to do" list.