really bad hunger pains..

So last night at 1am I was woken up with extreme hunger and hunger pains even though I'd eaten a hearty meal. I slept it off not thinking anything of it.. Then today I have had this incurable hunger along with hunger pains like the food isn't reaching my stomach, I've eaten and it doesn't go away I've tried drinking milkshake and it hasn't gone away.. The pain is horrible making me feel quite sick because I'm absolutely starving but nothing I eat is taking it away has anyone else felt this?! I'm 18 weeks 5 days