I sympathise. While I can't say what you're experiencing, I'm well aware of the very subtle differennce in myself between an anxiety attack and an addrenaline surge. The difficulty is the my doctor really doesn't have a clue and puts it all down to anxiety (I'm currently awaiting a diagnosis of pots from specialist). It is so hard to put this across because the symptoms are incredibly similar. My main difference is that with pots my heart rate usually (not always) calms on lying down and/or when all movement has ceased. With anxiety, it doesn't matter. Also, with anxiety there are usually triggering thoughts or emotions (such as grief or anger) beforehand. Adrennaline surges often occur when I'm particularly struggling, when I'm in a car, when there's a lot of movement around me or on waking up in the morning. It's hard but there is a difference. I hope you find some answers to what you're experiencing.