How to control mood changes?

I am prone to quick changes in mood and at times irritability (lack of patience). However, most of the time I am in a very good mood and would describe myself as a happy person with a lot in life to be thankful for. I really don't understand why suddenly out of the blue I can get a bad (sad feel like crying) mood but usually snap out of it within a day or less. Can anyone please help me with this? My great friends are aware of this and don't have a problem as they love me. The problem lies with new people and those who don't know me..I think I might be alienating potential friends.How to control mood changes?
Fatigue, insomnia, mental confusion, anxiety, nervousness, mood swings, faintness, headaches, depression, phobias, heart palpitations, a craving for sweets, cold hands and feet, forgetfulness, dizziness, blurred vision, inner trembling, outbursts of temper, sudden hunger, allergies, and crying spells are signs of low blood sugar. What do you eat? A lot of sugar? Skip meals? Junk?

http://hypoglycemia.org/hypo_test.aspHow to control mood changes?
maybe u have bipolar disorder. bipolar is basically where your mood flips from overly manic (feel really high and have little control and feel very happy) to real lows (depression, very sad, crying, dont want to speak or do anything with anyone).

defenetly defently go to your doctor anyway as you yourself know that this mood change isnt right seen as though u are happy in your life.

i cannot stress how important it is to go see your doctor and tell him about this, it could be thyroid problems, it could be stress, it could be a mood disorder such as bipolar or it could b nothing but if it is a disorder they tend to get worse the longer they are left. i went to my doctor, at first i was put on anti depressents but they made me ill and i only took one, a year later i went back to c another doctor and he refered me to mental health clinic, the doctor thought about bipolar disorder and now i am going thorugh the paces to get myself fixed.

dont be embarrased it could be the best thing you have ever done go see your doctor but dont let them just put you on a drug, ask to be reffered to a mental health team or psychiatrist etc
Exercise, eat right, get 7 to 9 hours of sleep per night, and see a therapist.
do things positive for yourself and others but dont let people walk all over you.