Dr Alex George admitted that 'grief hit [him] like a brick' as he struggled with the loss of his brother Llŷr, who took his life at the age of 19 in July.
In the caption of his photo, Dr Alex said: 'Grief hits you like a brick at times. Driving to work today it really hit me really hard.
'I feel so sad at times. I really miss my brother. I am sharing this because it's ok to feel sad. It's ok to cry. Miss you mate x'
Describing the moment his father told him about Llŷr's death, Dr Alex wrote in The Sun: 'In that moment my world fell apart, it came down around me, it shattered.'
The A&E doctor explained that his brother had no diagnosed history of a mental health condition and never told him how he was feeling despite being 'very close'.
Urging people to remember that there is 'no type' when it comes to mental health, he said that Llŷr did not share his struggles due to the stigma surrounding suicide mental health.
He continued: 'Not once did Llŷr tell me how he was feeling, I'm a doctor, we were very close, he knew I was a mental health advocate and hugely passionate about it.'
Dr Alex, who has been a mental health advocate for years, went on to explain that his pain from Llŷr's sudden death will no doubt be there for the rest of his life.
He added that his brother is always in his thoughts, as he shared his hope he will eventually be able to live alongside his grief.
He explained: 'That pain will be there for the rest of my life but at some point I hope I'll learn to live alongside it.'
The doctor, who works in A&E at London's Lewisham Hospital, took to social media in December to urge Boris Johnson to meet with him.
He penned a candid letter to the Prime Minister on Instagram, urging him to give more value to 'support for emotional and mental wellbeing' in schools.
He shared a snap of himself holding a handwritten banner reading 'Boris let's talk #mentalhealthmatters' alongside his lengthy caption.
The reality TV star said he has spent 'months' researching and speaking to charities and believes that mental wellbeing needs to be treated with the 'same importance as core subjects such as Maths and English'.
He explained that the issue has only become 'more important' due to the effects of the Covid-19 crisis, saying that each loss of life to suicide is 'potentially preventable'.
Dr Alex urged his 1.5million followers to share his call for action and tag Boris Johnson and Education Secretary Gavin Williamson, who he also requested to meet with.
His lengthy caption read: 'DEAR BORIS JOHNSON, Our children have a right to receive quality mental health education and support that adequately prepares them for the world in which we live.
“Too many lives are lost each year to suicide, each one of them a potentially preventable loss of life. How many more lives must we lose before we act?
'I would like to meet with yourself and Secretary of State for Education @gavinwilliamson.mp to discuss the changes which I propose. I look forward to hearing from you, Dr Alex George.
'Please tag @borisjohnsonuk and share to make this happen'
Back in September 2020 Alex broke his silence and spoke to Lorraine Kelly about the death of his brother
And the TV doctor did not stop there, as he also shared a flood of posts on his Instagram stories urging his followers to help him 'act'.
Speaking about his brother's death, he wrote: 'I might not be able to help my brother. But I can help other children and young adults, with your help. Together.'
He added: 'I have been quiet until now. Gathering information. Speaking to experts. Understanding the issue. Now it's time to act. Please help me.'
Dr Alex also fumed in all caps that 'our children have a right to mental health education', arguing that 'they deserve better' as he vowed he would not give up.
He also shared driven reactions from his fans, including teachers and practitioners, who argued that 'not enough' was being done to 'protect mental health'.
The doctor also posted an array of messages continuing to thank his followers for all of their support; His comments come after he endured his first Christmas without his brother Llŷr.
'I've been going through the hardest time in my personal life after loosing my brother Llŷr to mental health in July,' he told listeners. 'He was only 19 with a career in medicine ahead of him.
'I was so so proud of him. I miss him so much and he is always in my thoughts.'
Dr Alex also recalled what someone 'very very wise' told him after his brother passed away.
'Life throws us into the deep end at times but with the help of family and friends we overcome even the most seemingly surmountable of challenges. Just know you are never alone.'
Reflecting on the grieving process, he added: 'Grief is an ongoing process and I'll never get over losing Llŷr, but i want to continue doing the things that are important to me.'
A&E doctor Alex - who shot to fame on Love Island 2018 - was debuting the fourth series of the podcast after a trying year.
He's been treating Covid-19 patients at Lewisham Hospital in London and sharing his experiences with the nation in his role as a TV medic.
If you have been affected by this story, you can call the Samaritans on 116 123 or visit www.samaritans.org.