MICHAEL JACKSON IS HAVING THE WORST WEEK EVER!

FIRST, IS HE'S BEING SUED OVER THE JACKSON 5!
We've learned there was a secret meeting yesterday at the Beverly Hills Hotel, where Michael Jackson made it clear -- he will not perform with Janet and the Jackson 5; and the dude who organized the concert tour tells us he will sue them.

As we first reported, Jacko's manager signed a deal on behalf of M.J. to perform with his sis and bros at Cowboy Stadium in Arlington, Texas in 2010. Part of the deal -- that he not sign any other concert deal for 18 months. But then Jacko went and signed up for his London concerts which are scheduled to begin in July.

The company that organized the family concert --- AllGood Entertainment -- got Michael, daddy Joe Jackson and several others in a room yesterday at the Bev Hills Hotel. Joe tried to convince Michael that the family tour should go on, but Michael wouldn't budge because it would have aired on pay-per-view and M.J. said he doesn't like pay-per-view! The meeting was heated and no one agreed to anything.

Patrick Alloco of AllGood tells us he's going to sue Jackson and his family next week.

SECOUND IS HE JUST LEARNED HE HAS SKIN CANCER:

Michael Jackson reportedly has been diagnosed with skin cancer - but it's treatable and he still plans to go ahead with a series of London concerts.

The "Beat It" singer has cancerous spots on his body and pre-cancerous cells on his face, London's Sun newspaper reported Saturday.

"He was at first very concerned, but says he has been assured by the doctors that they can treat this and he will recover," a source was quoted as saying.

"He said he's insisted that any treatment must fit around the concerts, and the show will go on."

Jackson, 50, who already suffers from the pigmentation disorder vitiligo, has been visiting a Beverly Hills dermatologist, the paper said.

He got the diagnosis last month - around the time his car was involved in an accident at Cedars-Sinai Hospital in Los Angeles.

The report did not say which type of skin cancer Jackson has or what stage it is.

After years of legal problems, financial trouble and bizarre behavior, the "Thriller" idol is trying to make a comeback with 50 sold-out shows at London's 02 arena starting in July.