This happens to everyone at some point. I remember 1 time last year where I was going against 1 of the best teams in our league and just struggled from the get go. First game was well below my average (shot 106, was averaging in the 190's at that time). Playing outside had a lot of wet/dry, inside caused carry to suck, different angles and 2 different balls also gave varied results. That mental piece of it got to me to where I started missing easy spares. Plus, having several splits didn't help either.
The following week, I was able to rebound by shooting a high 600 series.
Advice I can give for when this happens is to try and keep the swing loose, take things 1 shot at a time, and keep the game simple. If you need to leave the seating area to gather yourself, do that also.