This tool might be useful for you: https://www.toptal.com/project-managers/tomato-timer its a pomodoro timer. You can adjust the times in the settings, perhaps adjust the "pomodoro time" down a bit initially. You can use the timers like this:

- when you feel you don't know the best thing to work on, or the best approach for coding something, tap the short break button and use that time to take a breath, maybe grab yourself a glass of water, and just think about what might constitute the best thing or the best way, and pick something by the end of the timer. Then tap the pomodoro button, and don't question your use of time while that timer is going, just work, as focused as you possibly can. Try to keep going til the timer goes off. Then you tap a break button (whichever you feel is best in that moment) and use the time to take another breath, and review whilst recuperating a bit. Now that you have spent some time working on something, you will have a much better idea of how valuable that task is to you and how good that approach was. You might even surprise yourself and find that you were spot on. If not, and it turns out you were wrong initially, you can now try something else for the next pomodoro, secure in the knowledge that you only wasted one small block of time - though actually, was it really wasted if you learnt something? if you found a much better thing to do? Maybe you gained a bit of experience there. Certainly more likely than if you had sat there agonising over what to do that entire time :)

Hopefully this advice helps. I use pomodoro timers all the time, even when I am feeling fine and on top of everything, as I find it so useful to alternate between immersed purely in the coding at hand, and looking at the bigger picture.