I also think a thorough medical work up is warranted here. It sounds like you have something going on that isn't at all depression or anxiety related. While SSRIs aren't well tolerated by everyone, they are not going to cause brain damage.
Again, I think you need to have a discussion with your doctor, rule out a medical cause. Ask for referrals to specialists if need be. The first one I would recommend would be a Neurologist.
Very best of luck to you, hope you get some answers soon, and some relief!
I have been on the antidepressant rollercoaster for about 22 years---and dealing with depression and anxiety for over 40 years. I had a horrible time tolerating the side effects, so i could not take most of them. if I managed to find one that would actually help---it would only last for a few months---and then poop out on me. I also tried ECT--but quit after 3 sessions--getting there was too complicated.
Personally, i would consider anhedonia to be one of the major symptoms of depression---I also suffer from it ( i had to look up what it meant!). Zoloft, and most antidepressants, make my skin crawl and give me the shakes. i also refuse to take another antidepressant again---especially since i no longer feel that depression is my problem---I believe it is a symptom of something else that is going on.
depression can cause hypogonadism---or lack of sex drive--that is a well known fact--but it should not be a permanent condition once you are off the medication. lack of sex drive or low libido, or both, is also another symptom of depression. personally, I doubt the colon problem had anything to do with the antidepressants.
I am wondering if you have an endocrine problem---specifically low thyroid. Hypothyroidism can cause all of the symptoms you are describing that you still have. However, none of the thyroid tests are accurate and will miss all but the most severe cases of hypothyroidism.
I suggest you try and find a doctor that is willing to treat your thyroid on a clinical basis, and dose you with a natural thyroidmedication until your symptoms improve, instead of dosing you by a blood test. In the days before the TSH test and synthetic T4 only medications, doctors had much better success in treating thyroid patients. just something for you to think about.
We can't give professional opinions as we are not professionals. Talk to a doctor or psychiatrist, although you only report one symptom of depression - anhedonia and that is not enough to be called depression. If you think you have brain damage you need to see a neurologist.
Never go off any meds cold turkey because the withdrawls can be hell on earth--you need the docs advice.