I have recently tried Deep Meditation again after a long hiatus from my practices. I stopped because I was overloading on just a few minutes of meditation with twenty minutes of rest once a day. When I started again I decided to only do five minutes so that I wouldn't overload. After about a minute or so my heart started racing and then I felt my heart beating at the base of my spine. The sensation then traveled to the top of my spine where it felt like the top of my back was expanding and contracting very rapidly. I told my brother and he referred me to this site. Any help would be much appreciated. Thank you and have a nice day.
It sounds like you are a bit to sensitive to be meditating with a mantra at the moment. I would recommend switching to breathing meditation for a while, maybe even a few months, whilst things calm down.
Also check out this page about over-sensitive meditators and what to do:
The symptoms you describe are caused by kundalini. They don't necessarily comprise energetic overload. Only if you are in pain or feeling anxious about what was happening would it constitute overload. If you are able to be relaxed about the changes in your heart rate and the energetic movements in your spine, then it would just be called "energy movements". Your heart beat can increase and it won't kill you, so you don't need to worry there.