What Causes Missed Period And Brown Spotting?

My period is 9 days late from my best calculations. I spotted when i wiped yesterday evening but nothing since except when i wiped this morning it was a little brown. I took hpt about 5 days ago neg. Never had spotting. Called doc yesterday before i spotted & he wanted to give me something to start period but i wanted to wait. Is this a period? Did i test to early maybe?