Amorim says United are now in the middle of one of the worst times in their history.
He said after Monday night's home defeat: "It is really hard. It is one of the worst moments in the history of our club, and we have to accept that. Another loss in front of our own supporters.
"In this moment it is really tough to turn around results because we don't have a lot of time to train the base of the way we want to play. In the bad situations you need that base to hold on to. In the second half they really tried, it was more like the value of the team. "We were close to scoring once but they were better.
"Yes we are (too easy to score against) but also in some moments we had some chances to score and didn't and that also makes a difference."
On if there's a danger of a relegation battle, Amorim added: "I think that it is a possibility and we have to be clear with our fans. We have to change something but this season will be really hard on everybody. It can make us stronger and we have to fight.
"I change something tactical in every game. You focus on the three defenders, you can focus on that. I change for every game and you can see it. If I did not believe I would change because I am not stubborn. I believe in something and I really stick on that."