Heart Chakra HEAT

[metaphysics]

Hi everyone,
I did a primary center stimulation session in trance, and as usual, each time I raised energy into my heart chakra, I felt an INTENSE heat sensation quickly build up then steadily rise up to my throat chakra where it continued burning for a while.  This happens as many times as I raise energy into it, and is intensified if I use any awareness actions on my heart center.  It feels just like really bad stomach acid (only it isn't This can even be triggered when I am stimulating my solar plexus, and to a lesser extent when I am stimulating my throat chakra.
Also, when I try to astral travel, the rush of energy flowing into my heart chakra causes my lungs to fully expand and billow violently totally throwing my out of the relaxed state.  This stomach acid effect is sometimes also be triggered by an astral travelling technique.
WHAT IS THIS???
And help would be greatly appreciated.
All the best,
Metaphysics