I know the feeling also. Two solutions
1) take a break completely ....... and start back again when the urge takes you
2) Build something completely different
Both have worked for me. Both have helped. And I feel both have helped me along. You come back with a new sense of interest and a will to be better.
Watch a couple of good war movies and maybe you´ll be surprised. Some scene may inspire you to build it.
That is also the reason I did not commit to this campaign. I felt stressed trying to meet deadlines and the hobby became more of a chore. Now Im only doing this one campaign (cover up) and if I have time i will do the RMG ... otherwise I´ll build something for me. Now Im back enjoying painting and building again!!