Weight decreasing

Hi mummies. Am so worried why my weight keep on decreasing. First checkup my weight is 63.8kg. And then 2nd appointment 62.7kg. 3rd appointment 62kg. But so far my baby is ok. My next appointment in 2 weeks time. But im just worried about my baby inside. Few days ago i ate something that cause me having constipation. But after that im good. Its just im back to vomitting. Should i worry about anything? ☹