Hmmm. Well you're on day 4 so, while great, that's super duper early. And if you were drinking while taking the drug you mention, its hard to say how it was really affecting you, know what I mean? So being tired and down on day 4? Very normal, hang in there.
I wouldn't see a GP for depression. I also don't think most MD/GP are particularly well versed in alcoholism....or depression for that matter. Both really are mental illnesses. So I'd recommend a good counselor with experience in depression and addiction. Here in the US counselors often work in tandem with a psychiatrist so if meds are needed that person can write the prescriptions.
I truly believe it takes some time sober to figure out where your addiction ends and your true psychological conditions begin. That's just my opinion and experience for what its worth.