I am currently under a lot of stress from different sources that are not interesting to mention on workplace but i am in a battle with myself.
The first port of call here should be to speak with a medical professional; they can make a proper assessment and advise on the best course of action medically (far better than anyone can here.) Two reasons for this - firstly, because getting the underlying problem sorted should be the priority, and secondly, because if you choose to speak about it to someone at work they then know it's a problem you're taking seriously (and you can produce a note from your doctor to prove this.)
I don't enjoy anymore working for the employer I am working for. [...] My question is should I talk to somebody about this at my workplace?
Once you've done the above, there's definitely advantages to letting your workplace know, whether that's HR or your manager (or both if appropriate) - they're then much more likely to be understanding if you're performing below par, or need to take a day.
However, you definitely shouldn't phrase it as "I'm not enjoying working here any more" - however much you try otherwise, that makes it seem as though it's your employer's fault, and you're looking to leave. That's not an impression you wish to create. "I'm struggling to perform at 100% at the moment because..." and "I'm finding things more difficult than I should at the moment because..." would be much better lines.