What to do when it all goes wrong?

Basically, I've played a number of seasons in the championship with Ipswich town. It always goes the same way, I will do well until like November/December, but then my tactic just stops working.

I have good players, but once it gets to this time I just can't win.

I'm curious, what do people do when this happens... How do you spot what the problem is? And what is the best way to solve it..

I'm talking generally, not tactically specific... It seems to happen whatever tactic I play!