According to a website about Grayson run by his mother Michelle Arroyo, he was diagnosed with a brain tumor on May 19, 2006, when he was just 6 years old. Michelle updated this website until August 2012, when she posted about Grayson's latest treatment. By this point he had been diagnosed with Diffuse Fibrillary Astrocytomas, which is a very rare tumor.

"The statistics say that only 46 percent of patients will survive this tumor at 4.7 years and 0 percent will survive at 10 years," Michelle wrote. Well, Grayson survived 16 years.

In a heartbreaking Instagram post, Michelle announced that Grayson passed away on Sunday, Feb. 5. While it was unexpected, Michelle mentioned that for the past few months, Grayson suffered from "fevers, infection, and low potassium," which might have contributed to the fact that his heart stopped while they were home.

"I performed chest compressions to get it going until the paramedics arrived and took over," but his "heart gave out again at the hospital," she shared.

Michelle's entire Instagram was devoted to Grayson, whether it was updating followers about his health or just checking in to share what he was up to. It's clear she gave everything to her son and wanted to make sure the life he had was as full as possible.

She finished her post with a hopeful thought about Grayson's next path: "I know Gray is playing cards with Gramma and playing Trouble with our beloved Diane. His dog Mo is right at his side as he never left him."