I Am 50 Yr Old Female. I Have Been Loosing

I am 50 yr old female. I have been loosing weight without trying from 147 to 135 since November. I have no appetite and when I do feel hungry I feel full after couple bites. I get up at 5:30 am and by 2:30 I am exhausted even though I work in an office. I am 5'4 and yes I am a smoker and I am white. Also bouts of forgetfulness. If eat more than few bites I get nauseaus.