You may want to see your general practitioner first for a complete check up with blood work. There are medical conditions that can cause mental health issues.

Your pdoc will ask you several questions to determine what medication may work best. It can take 4 - 6 weeks for a medication to take effect. Unfortunately, there is no drastic, immediate change. During this time you should keep in contact with your doctor if you have any negative side effects.

Your doc should see you every 2 - 4 weeks during this period as you try different dosages, possibly different medications and possibly additional medications. The only science to this process is how your body uses these meds, so it can be a bit of trial and error.

Not that you should anticipate my experience, but it took me a year before I hit the right cocktail. And even with that, as I've gone through depressive episodes, my meds have changed. In addition to talk therapy, my pdoc does pharmacology therapy so she knows meds extremely well.

As I mentioned there is no dramatic, immediate change. You may want to journal every few days about how you feel, how your sleep is, if you are dreaming are they nightmares, are you eating well, how is your energy level, how you are doing socially, ... This will help your doctor determine if your med(s) are working as they should.