you might need to go up. Call them and talk to them 50 mg of Zoloft is a pretty low dose so you probably have room to go up. I am on 100 mg and I was told I can go up to 200 mg if I need to.
I also have xanax when I am having a tough time.
I especially have a difficult time around my period which is very common. some dr.'s will have you go up on the medicine around your period (that is how many work with Zoloft) so there are many options for you probably.
Once my Zoloft started working I had about 3-5 days where I actually got worse around the one month mark. I was shaky, etc. I called the dr. and he told me that it is common when it starts working and I had to take xanax to get through it. Then I felt a million times better. So maybe you are going through the transition too.
so I would call the Dr. and talk to them :)