Why does my mind get foggy whenever I sit for spiritual work?

Name: Rhea D’Souza

DOB: January 11, 1997

Time: 12:15 PM

Place: Goa, India

When I try to medidate or even I try to manifesh something, my head feels so clouded. Earlier I used to see white light, but now, I see blank, or something bizzare images, and it blockes me from meditating. Is this a kind of negative energy in me. I want to have any crystal to cleanse this. What kind of crystals I could get to improve this?