Warwick got stunned for no reason

There was a katarina mid I came in to tower dive a low mid laner. Xerath i believe, panth came in from top at the end. Im not sure if he ulted or not. I think not cause he came in from blue jg. Anyway as soon as pantheon came onto my screen I froze until xerath was dead in between 3rd tier and 2nd tier towers close to the wall by red side. Very close to the entrance from tier 2 into red jg almost the edge of that corner. I also made a post about how Warwicks E seems to have glitched twice. Im not one hundred percent sure on that one, about 90. but this one I am sure I was stunned for about 4 seconds for no reason. No champions near me. Not even Xerath, I had basically given up on the kill cuz he escaped and I was low. but pantheon dove mid tier tower 2nd tier i believe at the back near inhib and killed him. then I was unstunned. I thought it was lag but nothing really indicated lag like more lag or re connecting