This really hits close to home for me. The first four years of my career I had the exact same sentiment. I would be able to complete my work in the first few hours of the day and just screw around after that. It was often misguided and didn't accomplish much other then learning random factoids. 15 months ago I finally brought myself to see a psychiatrist for depression, and between therapy and medication I was able to snap out of it and get on my feet again. The only thing is, while I started to love what I was doing again, I still felt no true inspiration to focus on something that wasn't truly challenging. And that turned out to be a major issue for me, and I had conversations with my therapist and she recommended I consider getting treatment for ADHD. One of my friends came by that weekend and happened to have a few extra extended release aderall, so I split it up over the two weeks between my next appointment with my psychiatrist. But I knew almost immediately after taking aderall that I likely had ADHD. I had a moment of clarity where my own thoughts didn't consume me while I worked for 30 minutes. The last time I felt that was probably a decade ago when I was still considering going to school for music performance. I've now been on medication for ADHD for a month and it's had a profound impact on my quality of life. I used to always be tired, regardless of how much sleep I got. I would find myself having difficulty in completing what should be minor tasks with any bit of precision. I was making so many little mistakes here and there that I didn't realize how much of an impact it was having on my morale.
This is a really long and roundabout way of saying, there's no reason not to go see a therapist and a psychiatrist if you feel like it's starting to impact you're quality of life. The worst thing that happens is you go to a doctor and get a comprehensive health examination to rule out any other factors or you take medication for a month that doesn't help.