After getting knocked out of the DFB-Pokal by second-tier Kaiserslautern, Leverkusen were then beaten in the Bundesliga by Schalke before going down 4-0 to Paris St Germain in the Champions League.
Saturday's 3-1 loss at Wolfsburg rounded off a dismal 10 days, which Kiessling hopes they can put behind them fast.
"I don't know what the reason is. We're all confused by the games we're playing," he told Sky television.
"Now we've got a normal week and we've got to sit down all together. Fortunately, we're not fighting for safety.
"If we had a solution, we would have used it by now. I don't think I've ever experienced such a 10 days."
Bas Dost gave the Wolves the lead on Saturday, but Sidney Sam levelled for Leverkusen on the stroke of half-time.
However, the hosts were not to be denied and Luiz Gustavo and Ricardo Rodriguez struck to take Wolfsburg to within two points of fourth-placed Schalke.
Leverkusen director of sport Rudi Voller was equally dumbfounded by his side's recent collapse. They have held on to second place, but the gap to fifth is now only four points, and the risk of missing out on Champions League football next season is growing.
"We've got to give our fans something next weekend against Mainz," Voller said. "We've got to put our foot down, like we did against Schalke, and then they will forgive us.
"We need to believe in ourselves and not be afraid of making mistakes now and again."