needing help! only a teen and don't know what to do

Briana

i noticed that i have linea nigra appeared and growing what seems dark and slowly growing bigger, im tired all the time , don't know if iv,e had spotting it was at least 2 1/2 days 4 days after the time of my missed period, ive been very nauseous, ive been trying to stay calm so noone says it blamed on stress but i am really scared, i get cramps alot during the day but they are light any help?