I started meditating last year. Once during meditation in one of your houses, I experienced a lot of heat in my spine. I got rid of my blanket & sweatshirt. I was so hot that I did not feel well. Up until that point, I would meditate gazing slightly upwards, first there was a lot of flickering, but then with practice the light became steady. After the heat experience my left eye shut. It is as if I was able to open both eyes while closed, but ever since the left one feels double shut.
What you have described (heat in the spine) is not unusual. It is something that often happens to meditators. It generally indicates that the kundalini energy in the base of your spine is being awakened through your meditation techniques. It is very important for you to discuss what is happening to you in your meditations with a qualified meditation teacher, perhaps the one who taught you to meditate.
As for the situation with your eye feeling shut, the same advice would be applicable. Talk with your meditation teacher and let them discuss this with you. It will be especially important to do this right away, if what you are experiencing (either the heat or the eye situation) continues to be uncomfortable or painful for you in any way.
Finally, be sure pray to God and your Guru (if you have one) for help and guidance in your meditations, especially at the beginning of each meditation.