prior to my diagnosis I was experiencing hot flashes. I was only in my 20's. When I was really "hormonal" I had suicidal thoughts at times and occasional homicidal feelings. Talk about feeling out of control. I'm a pretty logical person though and those thoughts and feelings don't calculate to me.
I did find my symptoms more extreme with generic levothyroxine and requested only to take Lavoxyl. I haven't tried Synthroid.
I do recall my physician recommending a daily vitamin supplement. Don't take it at the same time as the medication though.
There are definate symptoms of emotional imbalance when you have thyroid disease. I do not think it is med related - more a TSH hormones level as grizzelda said. When it is off alot of weird emotions can come up along with other hormone levels. I went into perimenopause early... just imagine the emotions that happen during that!! argh!!
I can't say for certain really any herbal rems that can help until you are stable with your thyroid. Until then experimenting isn't wise. It may send you farther into more hormonal imbalance.
I recall feeling very angry and irritable after starting treatment. Once I got level, I felt on top of the world. Is your TSH level? I function best at about a "1.0".