The `Behind Closed Doors` singer - who has two children Junior, five, and three-year-old Princess Tiaamii with ex-wife Katie Price - had to pull out of a recent public appearance and now has to undergo a series of medical tests to establish why he is feeling so unwell.
He revealed in his new! magazine column: "I`m sorry to say that I haven`t been feeling too great these last couple of weeks. I don`t know what`s wrong with me but I`ve got some ongoing health problems, and I`ve been having lots of tests at the hospital. I also had an MRI scan last week, so hopefully the doctors will get to the bottom of it soon.
"I just don`t feel right and I`m gutted because I had to pull out of the Pride Of Britain Awards because I felt so rough. It looked like a great night. Hopefully, I`ll be on the mend soon, though."
This is not the first time in recent years that Peter has suffered medical problems.
The singer contracted meningitis three years ago and later admitted he was terrified of dying from the illness after internet reports claimed he had passed away.
He recalled recently: "I completely freaked out. The thought that I could die from meningitis was in the back of my mind, but I certainly knew that I wasn`t dead yet.
"It set my mind racing. Firstly, I worried the doctors were not telling me something - that I was far more ill than they had led me to believe - and secondly, that my parents would have heard and be worried sick.
"I asked to speak to the doctor in charge of my case, who reassured me that if he had thought things were that serious, he would have had to tell me.
"So someone, possibly a hospital visitor or member of staff, must have started the rumour. But the psychological impact of hearing that I was supposed to be dead was something I would not wish on anyone."