Azaylia, who he shared with his partner Safiyya Vorajee, died in April aged eight months old.
Now, the former Coventry City player is helping raise money for eight-year-old Alexander who has been diagnosed with a brain tumour that is growing and has spread to his spine.
After donating £10,000 to a GoFundMe page set up by Alexander’s mother in November, Cain has started his own fundraiser, with more than £38,000 received in donations so far.
He is hoping to raise £65,000, which will cover the cost of a two-year treatment that is not yet available on the NHS.
In an update on 1 January, Alexander’s mother, Rhonda Josephs, said he has been on medication for three months and has shown significant improvement.
“Alexander’s spine is completely free of tumour, it is completely clear! The tumour in Alexander’s brain is also starting to shrink,” she said.
“Access to this expensive drug was made possible due to the fundraising, he is the first child in the UK to be given it straight after radiotherapy thanks to you.”
As part of the fundraiser, Cain also ran a marathon on Christmas Day alongside his brother and cousin.
In an update posted to Instagram on Boxing Day, the athlete thanked his followers and members of the public for their support and paid tribute to Azaylia.
“Azaylia you will always be the beauty to my beast. You not only made my life the best it could be for those 8 months, but you are making me the best me I can be for the rest of my life,” he said.
“I am forever grateful to you for everything you have taught me and to god who chose me to be your father.”
You can donate to Cain’s fundraiser here.
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