Sounds like you may have a underactive thyroid (Hypothyroidism), do you have any of the following symptoms, have they persisted for more than 2 weeks ?

fatigue, exhaustion, feeling run down and sluggish, depression, difficulty concentrating, brain fog, unexplained or excessive weight gain, dry, coarse and/or itchy skin, dry, coarse and/or thinning hair, feeling cold, especially in the extremities, constipation, muscle cramps,

Your doctor can give you a very simple blood test to see if your thyroid is underactive. I would suggest seeing a doctor.

---- http://thyroid.about.com/cs/basics_starthere/a/symptoms.htm