white

Seeing a white spot on one's underwear

Q: Sometimes when I go to the bathroom I see a white spot/stain. The thing is that the stain is there when I am awake. I mean that if I don't sleep for a whole day and then see it is there. Even If I don't get aroused there is a spot. It doesn't feel wet and neither does my private part fell sticky or slimy like its covered nether does my skin. This case is when I haven't slept for whole day after changing underwear in morning. I don't even feel anything if it there or while coming out if something does come out

1. Am I impure?

2. Do I have to change my underwear and do I have to do ghusul?