City have lost six in their past seven games and host Nottingham Forest tonight.
“It is difficult to answer because we haven’t really had this in all of the years we have been together,” Gundogan said.
“Of course, we had games and periods where we dropped a few points in a row, and we had to overcome these difficulties.
“We have to stick together right now. It is not a question of quality at the end of the day. We have showed over the last few years that this team is full of quality players.
“I think the mind plays a big role, but we have to use that in terms of getting on the training pitch and transferring that into work, desire and determination to go again and make things better because it is the only way out of the situation.
“Once that positive energy is created, there is no doubt things are going to be better again.”
On his relationship with manager Pep Guardiola, Gundogan insists nothing has changed.
“We have a very strong relationship, and we appreciate each other a lot,” Gundogan also told City's website.
“We have worked for seven years in my first spell and now again, so soon it will be eight years.
“In those eight years we have experienced a lot of ups, but also some downs which is part of the game and moments to appreciate as well.
“That creates a strong bond, not just with him but the players I have played with throughout the years.
“You live moments you will never live again in your life.
“That makes all these relationships even more special.”
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