I was driving on i-70 west heading to st. louis and i noticed air traffic was heavy. as i watched the sky more, i noticed a clean white light that had nothing blinking which i found strange. the way it moved was also strange as it went from side to side and then would suddenly change direction. i noticed it mainly because of it's movement and flight path. it didn't follow the flight path that airplanes normally take near st. louis which is along the southwest of the city, this was more north of the city but flying south. i first thought it was a helicopter, but soon realized that the speed it would gain that helicopters couldn't move like that. as i got closer, passing the staunton/lebanon exit, i got closer to edwardsville, il and the object. it seemed to have gotten lower, i would say tree top levels and was quite bigger than a drone. i thought it may have been one, but again, it moved too quickly and had such a spastic path. it also had no green or relights, it was only a solid white sphere. i had felt pretty weird when i first started driving and didn't think much of it but after looking back, i realized that the anxiety i get got worse the closer i had gotten to the actual sighting. as i watched it i felt so anxious and had a heavy feeling on my chest, which i haven't gotten before. as i passed the ufo, it was at tree top level and it was as if it shot straight south into thin air. following it was a trail of light with some green and purple in the trail but that was it. i watched the spot it was at and there were no buildings or trees that would've blocked my view, just a huge empty farm field. i was astonished and right as the ufo had left, so did the pressure on my chest. i am still in shock as to how it shot straight away into thin air, hate to say it, but almost as if it went into some sort of hyperdrive. this was my first real ufo sighting that gave me strange feelings and didn't get blocked by buildings or anything. i watched it clear as day as it came and as it left.