Ovulation test before period?

I have had the most awful nausea past few days but still getting negative pregnancy tests. 11dpo. Saw some people take ovulation tests throughout the month? I had 2 strong lines when I ovulated and then no lines as usual. Thought would try one today but don't understand it all. What does this mean if you have a faint line? Feeling really awful and I don't really get nausea before my period (due in 4 days or so)