To the end of meditation somewhere close to 30 minutes I started going deep that it felt like getting light headed. Had a nauseous feeling and I felt that if I continued I would go deeper and something will change happen. I still continued and became so fixed and concentration was not an effort at that point. But the depth and something scared me so much someway and I shook myself out and opened my eyes. Please guide me.
Experiences such as yours are not commonplace but do they do occur sometimes for some people! If ever in meditation you feel threatened or unsure of what is happening, you can generally just open your eyes, stand up if needed, and/or do some simple and deep breathing. In addition, call out to God especially in the form of one of the Christ-like masters.
It is important to use common sense in such matters and not to “ask for it” by indulging in seance or other activities that might call upon disincarnate entities. A true guru is a great help in such matters.
As to your practice of meditation here are a couple of suggestions:
1. Do not meditate in the dark. Always have some light around you.
2. Begin your meditations with a prayer to God or one of the gurus. Be ready to invoke divine assistance should anything come upon you in meditation that you are not comfortable with.
3. Consider meditating with eyes open, even if for part of your meditation. Have a picture or other representation of God or gurus on your altar.
4. I don’t know what practices you follow but in the path of Kriya Yoga (Self-realization) we engage the body through yoga postures, or energization exercises, and through some simple breath control techniques to calm the metabolism.
5. Is your physical or mental health posing any issues for you? Consider what medications you are on? Consult your doctor if there are concerns about the mental impact of medications.
6. Is your diet basically healthy? Do you fast (perhaps too much?) What are your sleep patterns like? Too much? Too little?
7. Any use of substances like alcohol or marijuana? Or ?
You can tell by now that I have encountered some people who have experiences like yours when the body and mind are out of balance for one reason or another. I know that in respect to the practices taught by Paramhansa Yogananda (including through Ananda) it is unusual for students to encounter issues such as yours. Therefore I am confident that if you explore my questions above carefully and faithfully and find someone to teach you time tested meditation methods, you will not likely encounter these symptoms for very long.
Lastly, I would ask if you have a meditation group that you are part of? And/or, a competent and experienced meditation teacher? Both are essential for those who wish to advance spiritually through meditation in a balanced and sustainable way.
We have many resources online and in person to help provide to you the company of like minded souls!
Blessings and joy to you!