Terrible headaches, constant exhaustion, hot and cold flushes, dizziness excessive weight loss...?

Im a 26 yr old female, i had a baby girl almost a year ago and i didn't suffer from PND. Over the last 6 months i have been losing an excessive amount of weight (30 kg's since having my daughter) and am now dangerously thin. I have been suffering from terrible migraines which i have a history of so it didn't concern me much. But lately im constantly exhausted despite having got a good nights rest. I get the chills and then all of a sudden im sweating im so hot. My neck is stiff and it feels almost like i have whiplash all the time. I have no motivation to do anything and have been feeling a strange lump on my head for the last few days that is really painful when i touch it. I don't remember bumping my head anywhere. I am having outrageous mood swings, i go from being irrationally happy to depressed in the blink of an eye. I do eat all the time and i have no history of depression. I also go through these stages where i feel stupid, and im not a stupid person,. Last week, my boss described me as acting like the dumbest smart person he knows. I have an extensive vocabulary but cant seem to remember anything.... I feel like im going crazy and i know i should go to the doctor but alot of this makes me sound insane and like a hypochondriac.... Does anyone have any idea whats going on with me?