Hi amdor
I haven't had any problems with this myself but I believe other people may have. here is part of yogani's lesson on chin pump that may help you.
In the beginning, there can be some side effects from the chin pump. They shouldn't last long. Some dizziness can happen. Maybe a slight headache. Maybe energy currents not experienced before in the upper body and head. It is a powerful practice, and we are making a bid to break through to a higher level of functioning in our nervous system, so there can be a few bumps in the road. For this reason, you may wish to begin your chin pump practice for the first time on a weekend when obligations will be less. Be methodical and don't overdo. If any symptoms become uncomfortable, back off practice immediately, and give yourself time to recover. Then you can come back later and try again, slowly. Honor your limits and use self-pacing. Self-pacing is very important with the chin pump. We are moving a lot of energy with this practice, up through channels where the energy has not been in such quantities before. And we are dealing with delicate components of our anatomy, our neck and head. If we want enlightenment, we have to nudge open the doors so the spiritual energies stirring inside us can find their natural neuro-biological functioning. The chin pump is a powerful way to open the doors between the heart and the head.