Sadio Mane underwent tests as he sought to find out why he was experiencing the "worst season of his career".
The Liverpool forward's struggles have mirrored those of his team as they face a fight to finish in the top four.
Their misfiring attack has come in for heavy criticism as they fail to produce the numbers of recent years.
Mane has scored just nine times in the Premier League which is his worst tally since moving to Anfield.
The 29-year-old admits he cannot put his finger on why he has experienced such a decline and went to huge extremes to understand why he wasn't performing.
He told Canal Plus : "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."
Liverpool's front three has been together for four years and, for the most part, started every game.
Their failure to perform like they have done has led to talk of an attacking reshuffle this summer.
Klopp though spoke earlier this season and claimed he wasn't concerned by his drop off insisting it is something all forwards experience.
He said: "For a player with the mindset of Sadio, he wants to do extremely well. But this is the situation he is in. Each striker in the world knows these kind of situations.
"I'm not concerned but I see it as well (that his form isn't the best), it's clear. We work on it. It's the only answer I can give."
