Had two patches in that seemed to last forever. First one was in tournaments that got me losing flips and bad beats coupled with some poor play. This was after having a fair amount of success early on. Being new to the game, it was blamed on about everything that you could imagine.
You really come to appreciate a site like this where people would ask for hand postings and share helpful advice. Basically I got up front and personal with Mr Variance.
Things got better and was back on track, feeling confident at the tables. Second bad patch was a decade later with SnG's. It went on for several months of really bad variance. Saving grace of dealing with it the second time, was the way it was approached. You come to grips with making the correct decision, but not getting the right outcome. People making bad calls and winning is a victory for you. You build bankrolls with those calls but you have to accept the times the don't hold.
Variance moved on, bankroll recovers and you move to the next plateau.
"Luck comes and goes but knowledge stays forever."
My biggest downswing actually occured recently and it went on for about 2 months straight. Couldn't win a single preflop all-in, got it in good and lost nonstop.
It was the type of downswing that an inexperienced player would not have been able to survive through after just a few days but I toughed it out and ended up winning back all I had lost and more shortly after the vicious bad beat cycle ended.