If you haven't all ready, try going for a period of time without expanding your mind and see if you notice a difference. I understand that you may believe it only takes 30 seconds for results but try to make it last longer; go slower. Like maybe try taking 5 minutes. I'd be willing to bet that its combination of the things mentioned - poor diet, proper excersice and technique lead to energy blocks. So maybe try to takea longer amount of time performing your technique and sorta run a self diagnostic - consider your blood pressure and heart rate, as well as breathing. See if you can notice any kind of emotional changes and recognize if their source is from within you or outside you. Basically look for any disturbances. Slowing the actual practice down from 30 seconds to even a mintute could give the information you are looking for.
Just some other health related thoughts - sleep, get plenty but not too much, either can have similar affects. And avoid high amounts of stimulants. When I used to drink coffee by the pot full by the end of the day I'd essentially crash, as well as disrupt my regular sleep. This resulted in fatigue and head aches as well as muscle spasms and higher anxiety levels.
As far as seeing a healer I'd try to heal yourself first before you put yourself out to somebody who may or may not be real. If you do all the things necessary to live a healthy life, remember health is on three levels - mind, body and spirit, then any energy blockages should clear up on their own.
In somewhat psychological terms, my psych teacher would shoot me for trying to equate occultism to science, what you're doing is a kind of dissociation. If you don't already know is basically the conscious and/or sub-conscious mind seperating itself from a given state of being. In its extreme form the mind does it to escape trauma. People with with multiple personallity disorder suffer from a dissociative disorder. You've probably heard about various cases where people who were raped felt they left their body during the attack. Same for people are abused in other ways. Lesser forms of dissociation are like feeling test or date anxiety and taking a step back from the situation to collect and calm yourself. Mediation is a form of dissociation. In order to expand your mind and sense whats beyond yourself you seperate your mind from your present state of being to feel whats outside of yourself. This alone can cause headaches. It may simply be a reaction to the technique. There might not be anything unhealthy about yourself. Your brain, in its infanitly complex neurological matrix, may just generate headaches.
To me, from my "mystical" stand point, these headaches imply that you are not properly grounding yourself after you complete your excercise.
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