I Am A 41 Year Old Fairly Healthy Woman On

I am a 41 year old fairly healthy woman on anti-depressants and methadone. I have been on both of these for over 7 years. i have recently started experiencing fainting spells mostly at night if I wake up to get a drink of water or go to the bathroom.. Last night really scared me as I hit my temple very hard and hurt my arm and knees. I have had a headache all day today. Can you tell me what may be causing this