With just four games left to play in the Premier League, the Reds sit in sixth spot - six points behind fourth-placed Leicester.
This season Mane has managed just nine Premier League goals despite featuring in 31 games.
He told Canal+: "This is the worst season of my career. I have to admit it.
"If you ask me what is wrong I will struggle to give you an answer. Personally I don't know.
"I have always tried to be positive, whether things are going well or badly. I question myself all the time.
"I even underwent a test to take a look at my body. Am I eating the right foods, or has everything changed?
"But they checked the test results, and everything is fine.
"I need to understand that in life there are ups and downs.
"I will keep on working hard - and perhaps in time this situation will pass."