Found a spot/lump on outer vagina, is purple/red, about half cm in width and isn't sore. should i be worried? scared it may be a tumour.

Tumor unlikely: What you described suggests that h lump is a Bartholin cyst. It forms due to blockage of a gland near the opening of the vagina. There is no urgency, unless the cyst gets infected and becomes painful. You can wait to have it checked out at your next visit to the doctor. You may consult this site for info in this topic: http://www.mayoclinic.org/diseases-conditions/bartholin-cyst/basics/definition/CON-20026333