All I can say is that you are the only one that knows what you saw. If you believe it's not a jet then keep looking. To me I can't see anything
but contrails. The one that disappears happens all the time when jets hit different temperatures in the atmosphere. Maybe you'll get luck enough to
video tape it and we can see what you're seeing.
the thing about it is the jets and weird balls(ufo's), i can see them when they fly but the camera can't pick it up. when it disappears the trail
doesn't just disappear the entire ball does.