WARNING: TMI ALERT

Ok. Sorry for this but I need some help. I'm like. 17 days late on my period, and I've been feeling off. Haven't had any symptoms of starting my period or anything. Last night I had some kind of discharge. yellowish kind of but no smells or anything. I called my doctor and she said there was nothing to worry about. well this morning I thought to put on a feminine product to help protect my panties and fell back asleep. when i woke up i noticed there was some blood and didnt think anything about it and went along my day. the nausea and dizziness got worse so i laid down and slept for most the day. when i woke i went to change my product and theres not even enough there to change. not enough blood to even be considered a period. what could be wrong?