Dear Katerina
When I first started reiki, also about six years ago, my hands used to get extremely hot - to the point of virtual discomfort. And strangely my heels as well. The reiki flowed strong and effortlessly, but I was concerned ... seeming on the point of spontaeous combustion!
I did a posting on this message board, and the clear consensus which emerged in the response was that I should practice "grounding". Accordingly I started doing Tai Chi and Qi Gong, and after a while the energy started to alternate between heat and cold. But in my experience, both are effective and relate to what the person being treated needs.
I am not sure whether the cold energy is cold reiki, or the cool earth energy that some qi gong practitioners refer to. Frankly, I not sure if it matters. To me it's all good :-)
Go well
Strelizia