My thyroid is not a problem. However, my Vitamin B12 and Vitamin D were low. Maybe I am losing all my vitamins to my breast milk? Anyways, I have just recieved my first B12 shot today (sore right arm!) I also have prescription-strength D tablets to start taking. So we will see if my mood improves once I have more vitamins (and my 100 mg dose of Zoloft) in my system.