1. There is something else which is pre-occupying your subconscious mind. Probably something which you are trying to sideline as not a big deal, but subconsciously it is a big deal. Find out what that is and take care of it head-on. This will fix itself after that.
2. You might not see yourself being 'successfull' in this job over a longer term. For example, you want to do a startup and even though you need this job for the money, you still understand that your longer term interests are better served by quitting right now and doing a startup. It could be something else but essentialy what could be happenning is that your subconsious realizes that you doing this work is not getting you any closer to your longer term goals and hence it is revolting.
Do not seek to change yourself or your circumstances right now. Only seek to understand yourself - once you have done that these things will go away by themselves.