It is difficult to figure out why you had those experiences without knowing much more about you and what is going on in your life. If you went to a doctor (a good doctor
) she would probably want to know how you have been sleeping, how is your health in general, how your diet is, any work stress, relationship stress, other causes for concern. And then, she would want to know what exactly were you doing in the yoga practice: which poses, for how long, were you having your period, did you eat well that day, how had you been feeling before practice. In this questioning, we could start to sense how much of what you experienced was due to the practice, due to other things happening in your life, or due to an unfortunate combination of both things. Or maybe, you were coming down with the flu?
Sometimes people can get a headache in yoga when they hold certain postures too long, like inversions. There is a thread on the forum that talks about headaches after Yin yoga: you may want to read this
. Your problem may be as simple as avoiding a certain pose, but you didn’t mention which postures you did. You also don’t say how long you stayed in the poses. Could you let us know a bit more about your situation?
Most importantly, how are you feeling now? Were the symptoms short term, or were they long lasting. Finally, please don’t take medical advice from a yoga teacher
If you are concerned and this happens again, check it out with your health care provider.