My scar from appenditicis about 13 years old suddenly turned bright red, stretched and a bit hot. should i be worried?

Possibly: If it is turning red and the redness is spreading out from the scar you need to see a doctor as that could be a skin infection.

You may have: a superficial infection of the scar tissue. Usually your body's immune system will take care of it, but if it gets hotter, redder, increases in area, and more painful, you need antibiotics right away. If you have any problem with your immune system (pregnant, AIDS, chronic illnesses or steroid-dependence) then you need to see a healthcare provider right away. Thanks for trusting in HealthTap.