The Premier League champions have two wins from seven games this term and followed up last Saturday's draw at Newcastle with a midweek Champions League loss at Porto.
"I define (this) as the worst period of my career, with the worst results in my career," said Mourinho, whose side host Southampton this weekend.
"I get it as a fantastic experience - an experience that I don't want to repeat
I want to finish tomorrow and win some matches again.
"I think it comes too late, to come after 15 years is too late, but it's something that is helping me to be better, a great negative experience."
Mourinho insists it is not the most challenging period, but the worst in terms of results.
He said: "I had a big challenge all the time
It's the worst results
I've never lost so many matches
That's a fact."
The challenge began on the opening day of Chelsea's title defence, a 2-2 draw with Swansea on August 8, the repercussions of which continue.
Mourinho criticised first-team doctor Eva Carneiro and head physio Jon Fearn for going on to the field to treat Eden Hazard.
And Mourinho was cleared by the Football Association on Wednesday of making discriminatory comments towards Carneiro.
FA chairman Greg Dyke has told officials that Mourinho committed "a failure of his personal judgement and public behaviour" in his criticism of Carneiro, while independent board member Heather Rabbatts launched a stinging attack on the FA for its "seriously disappointing" handling of the case.
Mourinho refused to respond on Friday, saying his comments will come in time.
"For the past two months I didn't open my mouth and I'm going to keep it like this
One day I will speak and I will choose a day," Mourinho said.
"I'm quiet about it for a long time
I read and I listen and I watch and I'm quiet.
"I'm telling you, we can be here all day
My time to speak will arrive when I decide."
Source : PA