If you can't make the history work, if things feel off, if the timeline you envisioned just isn't working out, quit trying to make it work and rewrite it already. If it isn't working right now, it isn't going to start working five chapters from now. And I should know. I found this out the hard way.
Rewrites are really the worst. No freelance writer wants to rewrite something they already wrote, and no author ever wants to go back and change a story that's already down on paper. But sometimes, what you've written just isn't working with the rest of what you still need to write. Stories can be tricky like that. And before they trick you into writing 100 pages too many, go back and rewrite.
Things don't always work out on the page the same way you planned them to work out in your outline. Even when you write exactly what you planned, it doesn't always convey the right message or tell the right story. This is what happened to me during the first draft of my latest project. I had things all planned out as far as what information I was going to reveal, but in looking back at it I found that I was revealing too much. Too bad it took me an extra 5 chapters to figure that out. So now I'm rewriting, and I'm putting the story in its place.
If something doesn't feel right to you or the story isn't working or something just doesn't fit, don't wait for the problem to fix itself. Rewrite, regroup and continue so you can carry on. Rewrites are a part of every writer's life.