Finally I have found an explanation. Had been having Acv in salad dressings but r centky started Keto way if eating and bought supplements and Acv. Took supplements and then drank half a pint of water with half a tablespoon of Acv. Suddenly had this weird feeling and panic attack - felt like low blood sugar or low blood pressure. Thought it was maybe interaction with the supplements so cut the supplements and next day had a few drops with avocado and boom - heart racing - heart rate up - panic attack - no more Acv for me.