I was just toughing my neck near my pulse on the left right. and i kind of pressed on it. there was a lump but it is not visible because you have to physically press in and rub it to feel it. It's was like a small ball at first but then as i kept on rubbing it, it flattened down, but i still receive a soreness from it compared to the right side of my neck . Do you know what cause this? I told my teacher this and he said it may be dehydration but i have been drinking water today.