All yoga sends energy up through the 7 chakras and sushumna nadi (roughly spinal column). Hatha too. It's called prana or upward movement. To send energy down I would recommend sitting for hours in front of the tv with a bag of doritos. Wait a minute, everyone is doing that already!
Power yoga or ashtanga yoga is really no different than Hatha. What it means here in the west is that you can expect a more vigorous aerobic class and to sweat a lot. In terms of benefit physically, psychologically and spiritually, I believe that it is no different from Hatha. They both have the same roots, just a different way of sequencing the asanas (postures).
I have a doubt that the problems you were experiencing were the result of a yoga practice. It IS possible that someone practicing too much in the early stages could cause some emotional disturbance or physical pain. It is also possible that too much pranayama (breathing exercises) practiced in the wrong environment and without having achieved some purification first, could do the same, but you do not mention that you were doing this. Pranayama is powerful stuff. I can't see what you would be doing to get energy "stuck" in your chest unless you were doing something really wrong or unconventional with your practice, and I can't imagine a qualified teacher causing that to happen. Often though, a yoga class will bring all the old skeletons from your mental and physical closet, so it could have brought out an illness. All working towards a state of health and freedom from disease.
However, I can't 2nd guess what this guy said. I would suggest that you get well and address whatever health concerns are there and then to incorporate an ashtanga practice again when you feel strong and ready. Start slowly. Continue with hatha.
Oh, know anything about Ayurveda? People with too much internal heat in their body (Pitta types) don't do as well with Ashtanga because it generates too much heat and doesn't allow for cooling off periods. Just another thought.
Weird, energy moving down! I'd love to know who this guy is. Certainly the goal of ANY yoga is not to move energy down. Reaching toward our higher natures and that feeling of lightness...
Have a great day,