Medication has two effects: one primary and one secondary. The primary effect is to physically stimulate you into a state of well-being, like taking drugs, but as soon as the effect wears off, the secondary effect kicks in, leaving you, just as drugs would, wanting more, being more depressed. Anti-depressants are basically just another form of drugs, and leave you feeling the same. In short, they do not work as a long term cure.
On one level (a kind of spiritual Buddha level), you might say that there is no such thing as depression. You think yourself into depression and then it becomes a reality to you. The whole spiritual thing is about undoing those thoughts, realizing how they create your problems and therefore are at its’ root and then making peace with them. You use the term ‘constantly weighing on my mind to the point that I can’t think about anything else’. That is precisely the problem. But what is it that’s weighing on your mind? Look closely! Is it not a constant stream of (negative) thoughts about work, thoughts about certain colleagues, thoughts about how they treat you and so on? Is it not at the point of these thoughts appearing in your mind that you feel depressed? No thought, no depression; thought appears, depression. That’s how it works.
By seeing into the mechanism with which we create our thoughts and therefore depression, those thoughts automatically loosen their grip on us. The deeper we ‘see’ into our minds and understand its whole nature, the more we undo the whole foundation of problems in our lives. Clarity and freedom from an inherited lifetimes’ worth of cultural conditioning is what you really need for long-term peace of mind. And it can be gained in an instant like being hit by a bolt of lightning. A sudden jolt of realization can lead to a dramatic shift of consciousness, and it can be all over.
I know all this sounds a little other-worldly at this point, but there are practical and very simple steps that you can take to ease you into a clearer mind frame. I would be happy to try and help (for free) if you are willing to give it a go. I think you will walk away with a huge smile. If it doesn’t work, then you can always try your merry-go-round of counseling, medication, socializing and so forth after (at a great cost).