Small, hard, pea sized bump on forehead since 2 weeks. not painful, itchy or bleeding. under surface of skin and has purple hue. cancer?!

Watch for size chang: It can one of several different things. Most such things are pimples and will settle down in 2-3 weeks but watch its size and look for color changes. If it grows in size over the next 2-3 weeks, it should be shown to a doctor(PCP or dermatologist). You need to make sure it is not melanoma which case it will like increase in size in 2-4 weeks.