Aloha Nacho,
I just getting to some of these after the retreat...
When itching, aches or pain show up as channels are being opened, call upon your master's energy to assist you with the work your currently doing. Since your doing Master Lin's work, he'd be a good one to call on.
The feeling on the other side of the discomfort has for me, been a huge shift in energy, awareness and being.
A friend would get pain in his lower back while doing the full lotus and finally decided to open up to the energy in the pain and be with it until it released...it took four hours, but did release.
Much Love, Shawn