I have bluish lips too. Actually, along parts of my lip line there are dark purple areas. I would guess that the reason your lips are blue and get more blue upon exertion is POTS (I also have POTS (dysautonomia) as well as EDS, Chiari, MCAS so I feel you). Just like how blood rushes to our stomach after we've eaten, and can cause post-prandial (after a meal) POTS symptoms like extreme fatigue, increased hear rate, lower blood pressure, etc. We feel this after a meal because the blood is rushing away from our head, lower body, etc and goes to the stomach so the heart has to pump harder to move blood around to all parts of our body. I think when you are exerting yourself, you are increasing your heart rate to oxygenate your muscles, lungs, brain and the body thinks of the extremities as second class citizens for a bit. Its main concern is oxygen for the major muscles and organs. This will cause tour lips to get blue. Same with laughing. It is an adrenaline rush which does a similar thing as exercise. Our bodies only know processes. It doesn't know the difference between laughing hard, exercising or running away from a tiger. It reacts in similar ways. Really, the first thing that happens are autonomic processes. Things your body does that are controlled by the parts of the brain that don't require any input from you. It just reacts and that saved lives back when the threat was real. I would suggest you look into brain stem compression from Chiari Malformation which is often tied to POTS. It may be that you have dysautonomia from a structural issue rather than just POTS. Lastly, get your iron checked as well as B12. If you are anemic, it will make 3 everything else with POTS worse. I know that post is pretty old now but I have been looking for proper treatment for my issues for 14 years and still searching. I hope you've found answers but if not, i hope this helps or helps others who have found themselves on this website.