The sexual energy work up the spine is actually the following - you are running extra current through the spine nerves up the spine, through the hind brain into the brain. Sorry, but I never thought that was a good practice to start out with, and it is difficult to tell when you are ready. You would need a good teacher to guide you.

Another rule of energy work is that "Where the energy goes, the blood goes." - that might explain the bleeding. You're basically raising blood flow and oxgenation. When you run a lot of energy, you do that very fast, though. Unelastic and brittle blood vessels might cause spontaneous bleeding - I had that experience with my nose over and over. Really big nosebleeds after a meditation session trying to "watch the breath at my nostrils." (A practice always portrayed as not having even the possibility of ill side effects - quite unlike sexual energy work.) These problems can be IMO cured over time by carefully and gently (!!) doing energy work in the affected areas, removing minor blockages and making the blood vessels elastic and strong again. Again, that's not done by rushing a full orgasm of sexual energy there, but by sitting down and working the problem as quiet as in meditation, softly.

Directly doing energy work of the brain is also often considered advanced. General order is something similar to muscles and tissues first, then the organs and glands, and finally nerves, brain and its glands last. Circulating sexual energy to the brain should be preceded by first cleaning the spine, also by generally removing blockages in the brain (see above). Only after stabilising the system this should be done. I know some do this with success right away, but that is the luck of birth. If you have side effects on first try - well, you don't have the luck of birth then.

It can be done when the different circulations have been thoroughly practiced, stabilised and are open. But I have yet to find someone who even published about all the circulations involved there - I've read there are as many as 18 (!) different variants of the circulation that can be opened in established orders. That person - Bruce Frantzis - trained 7 years as a Daoist priest to be given all that info, and he teaches that stuff no longer publicly. He used to, though.

I know some recommend this practice, Mantak Chia does, but I think that's irresponsible, as some people with a more sensitive nervous system could get hurt - I think you should take your experience as a warning sign and drop the practice altogether.

Sexual energy can be very potent. I've read warnings that the mind should not be agitated when working with sexual energy. So it is surely not the right state of mind when having sex to move the energy around unless you trained your mind to experience as a calm observer.

My personal opinion is that sexual energy work is best left alone, and there seems to be no real consensus about this within the Daoist community.

Oliver