Is mindfulness making us ill?

Iam sitting in a circle in a grey, corporate room with 10 housing association employees – administrators, security guards, cleaners – eyes darting about nervously. We are asked to eat a sandwich in silence. To think about every taste and texture, every chewing motion and bite. Far from being relaxed, I feel excruciatingly uncomfortable and begin to wonder if my jaw is malfunctioning. I’m here to write about a new mindfulness initiative, and since I’ve never to my knowledge had any mental health issues and usually thrive under stress, I anticipate a straightforward, if awkward, experience.
Then comes the meditation. We’re told to close our eyes and think about our bodies in relation to the chair, the floor, the room: how each limb touches the arms, the back, the legs of the seat, while breathing slowly. But there’s one small catch: I can’t breathe. No matter how fast, slow, deep or shallow my breaths are, it feels as though my lungs are sealed. My instincts tell me to run, but I can’t move my arms or legs. I feel a rising panic and worry that I might pass out, my mind racing. Then we’re told to open our eyes and the feeling dissipates. I look around. No one else appears to have felt they were facing imminent death. What just happened?
For days afterwards, I feel on edge. I have a permanent tension headache and I jump at the slightest unexpected noise. The fact that something seemingly benign, positive and hugely popular had such a profound effect has taken me by surprise.