13 weeks pregnant and throwing up again

From 4 weeks until about 9 weeks I was sick all day barely held anything down between water and food 90% came back up so for the last couple weeks I've been fine just a little nauseous here an there. Now two days ago I woke up wicked sick an throwing up an pretty much back to where I was before is this normal to happen I'm taking the b6 and unison not helping me at all. I haven't weighted myself but I don't even feel like I have put on any weight just losing it down almost 20. Doctor said she isn't concerned that I'm losing but it just doesn't sound right to me.