Dizziness/ Nausea

Hello all,
I have recently been learning a "sitting" qigong taught by my shi fu. Lately i have been getting very hot(whole body)/ dizzy/ nauseas about 10- 15 min. into it. Up to that point it is beautiful, then the dizziness/ nausea creeps in. I close out and stop. I try to reach the 20 minute minimum at least. This has just started happening this week out of the blue.

My shi fu says she feels it is my body healing and if i need to puke, let it out, dont hold it in. Hehe, right in the middle of class ??? Yuck.

I went thru some serious lower back/ kidney pain for the first two weeks, as well as other aches, pains, heat, cold, etc. in various areas (healing many years of external arts injuries). Now for the most part the discomfort is gone and it feels great, untill it doesnt.
Anyone ever have simillar experience?
Regards,
Dave

"Character consists of what you do on the third and fourth tries"