No appetite/nausea help?

Krysta
I'm a week and a half postpartum and started having horrible symptoms of PPD before I even hit a week. I finally went to my OB this past Monday and was started on Zoloft 50mg with .25mg Xanax to help fight the anxiety and panic attacks until the Zoloft kicks in. 
This has been a problem since we left the hospital but has gotten so much worse this week. I have zero appetite. Nothing is appealing, not even my favorites. I could literally not eat all day. But, due to this, and possibly as a side effect of the Zoloft, I'm insanely nauseated. I also have endless stomach cramps like I'm ridiculously hungry even though I just ate 15 min earlier. Those cramps come and go.
I've been drinking nutritional shakes to take the edge off so I can eat but does anyone have any other suggestions? How long will this go on?