Nausea

So I’m currently 21 weeks and the first trimester I had severe morning sickness that lasted 24/7. By around week 16 it went away completely but as of the past couple days it’s come back. I can’t eat anything and I’m vomiting again. The first trimester I lost 15 pounds and then went to the dr Monday and had lost a couple more. They aren’t worried. Anyone else have this happen? The sickness go away for a few weeks only to come back? What did you do?