I had bad morning sickness from around week 9 until 17 - actually, it was all day sickness
I found I had very little energy and was very tired. As others have said, try to eat even a little and often. I used to find having a couple of ginger biscuits in the morning helped and snacking on some fruit or yoghurt mid-morning and mid-afternoon. I used to feel worse if I didn't eat and you need to keep your strength up.
I hope it goes away soon for you. I know it's a really draining feeling.
Good luck
