Gaining weight but feeling awful :(

So I just had my second doctor appt and ultrasound and I have gained 4 lbs in 3 weeks despite throwing up almost every day. If I am eating, I am not throwing up. It is when I stop eating that I lose everything in my stomach. I also haven't worked out in 2 months because I work, then throw up, then go to bed at 7pm exhausted. Does anyone have suggestions?? I am at a loss.