The 38-year-old mum-of-one explained that doctors had found an "area of infection that somehow found its way into the brain", meaning Solomon needed another operation to treat the infection on Sunday morning.
Natasha added: "Feeling gutted but also thank God that we live in a time of MRI where we are able to see into our own minds and for doctors who are wise enough to keep asking questions.
"He has an area of infection that some how found its way into the brain. We are so grateful though that there is treatment for what Solo is experiencing and it is straight forward and has worked many times."
The star asked her followers to keep her son in their thoughts, she said: "Please keep him in your prayers and meditation tonight and tomorrow.
"The body has amazing natural defences so we just need it to do what it does with a lot of extra help from modern medicine .
"When you have been in the hospital for 3 weeks, time stops. I'm realising that this is not a quick in and out visit . So this week will be about making sure we ourselves are healthy and also that we are giving solo good nutrition to help keep up the immunity."
Natasha shared that she was forced to leave her little boy and fly to Las Vegas for a "quick show" she had agreed to prior to her son being admitted.
"I'm actually on a plane to Vegas tonight to do a quick show I was committed to and then come back in time for the the surgery. Love u guys. Life is crazy. This is the real rock and roll," she said.
Natasha and Matt tied the knot in March 2009, in an outdoor ceremony at the Church Estates Vineyards in Malibu, California, and welcomed Solomon on New Year's Eve 2017.
“Now the bump is starting to really show, it’s sinking in that this is really happening,” she said, adding, “I’m so excited to embrace this huge life-change. And Matt is super supportive.”