Firstly, AME's definitely differ in their attitude. My original one used to joke with me about putting ancient pilots into a darkened room for 10 minutes before the ecg.
Secondly, try a few mind relaxation exercises. Plenty on the web these days, but I was taught one by a BA medic years ago which takes only a minute or so, but appears to work
THirdly, if BP is the issue, consider Beetroot juice (most supermarkets have it). Tastes pretty grim, but does lower my BP a few points if taken for a week or so before the exam, do make sure that it won't interfere with your medication.