Up and down sickness

I still feel sick I'm 10 weeks but have been on the 7 th different morning sickness tablets been taken them for about a week they were working grate why have they decided to not work as well or is it just that I'm now ten weeks I have 3 children already and around 12 weeks it's completely gone I pray it's gone at 12 weeks otherwise I'll be devistated as I'm not sure how much I can take of this awful feeling 😩