Talk to Gynecologist on Pregnency N Vomiting

I m 10 weeks pregnent. Its 3rd pregnency. I m having v bad nausea n vomiting all the time not able to eat any thng whole day .taking onset tablet but its also nt working. Even if i drink water it mostly comes out in form of vomit. I m over w8 100 kgs n in 6 weeks i have loss 12 kg.. kimdly let me know wht to do so i can digest little water n food i m v much worried about the fetus health .thanks alot