I m not sure if it is a vein or what exactly the lines on the bottom of the tongue are, but on the left side the entire line/vein is red and sore, and it causes pain when I eat/move my tongue certain ways. It also feels like it is sticking out more than the one on the right, as if it is swollen. I found out I had strep a couple weeks ago, and right before that was when I first started noticing this particular issue. Since it hasn t gone away, or even started to heal at all over the course of those couple weeks, (at least not that I ve noticed) I m not sure if I should be worried about it or not.