It is just your body adjusting to the divine soul growing inside you. Those early hormones rise quickly, causing this sensation, so stay positive and take rest.
It's because of the sudden surge in hCG and estrogen hormones in the first trimester. I used to feel so miserable every morning, did anyone else also feel it lasted all day?
It's mostly because of rapid hormonal changes in your body. Just make sure you are not drinking sugary juices to stop the vomiting, instead have small bland meals.
I totally understand how exhausting it is, dear. Your body is working so hard to grow your little miracle, and those rising pregnancy hormones like hCG are the main reason for this sickness.