HELP?!?! LOST 7 POUNDS IN 2 WEEKS???

I'm 19 and just got Nexplanon 2 weeks ago. I've already lost 7 pounds and have very little appetite. I stopped the pill to go on this.

I am 4"11 and was 110 and am now down to 103.4 pounds.

I know I am naturally tiny, but the pounds are coming off fast. It is weird to me because these 10 pounds I gained from the pill during 8 months on it would not come off.

I has really bad diarrhea but that went away (TMI sorry). And I felt really nausous today. I almost threw up, like you know that weird tasting spit thay comes up before you puke? It was like that for a couple minutes.

What is happening to me? Is this normal?

Thanks in advance!