What Causes Crossed Eyes?

all of a sudden 2-3 weeks ago I started feeling like my eyes are crossed(when I have these experiences people say there s nothing happening with my eyes) and can t see straight and it s been happening several times a day at the start to now almost constant.progressively getting worse...no known medical issues and no headaches ever...literally ever...I am getting to a point it s hard to look at any one thing at a time and affecting my every day life since I m not feeling focused (visually). no.medications surgeries, illness, family history..any ideas?