Dude. I am not unsympathetic to your problem here. Because it's a problem we all have here: severe anxiety.
More tests will not cure it. The biopsy result, the clear CT scan you'll get shortly, aren't going to help. Remember how you thought the colonoscopy would reassure you that you didn't have cancer? It told you you almost certainly don't have cancer OR anything that will lead to it - and here you are still.
Please, get a therapist. Keep taking your zoloft - it can take a few weeks to have an effect.
You can get through this and live your life without the obsessing and panic.