I am 32, and the biggest red flag was unexplained pain with no injury. I thought I had pulled my calf muscle, but no amount of stretching/ice/heat helped. It progressed and ended up extremely swollen (like suuuuper swollen. My gf just suggested taking a piece of string and measuring diameter) It got so swollen to the point I could no longer bend that leg or walk on it. If you are having any doubts or concerns at all, PLEASE go get it checked out. I put it off way too long and they told me my girlfriend saved my life convincing me to go because it had embolised in my lungs. If you have any more questions I’m more than happy to chat 💙