Can LPG treatments cause dizziness?

I just started LPG. The first 2 times I felt a bit out of it but drank a lot of water, then felt much better. However the practitioner was a bit weak. Yesterday I switched to a new one, who was more aggressive. I felt during the treatment I was fading out a little. After I drank LOTS of water but felt dizzy, queasy, drained and very cold. Today I woke up with a huge headache and lethargy. Are these normal side effects? Or is it all in my head? I tend to get anxious. Should I stop the treatments?