Alex, now 35, suffered a life-changing ordeal after a common cold caused him to develop a strep A infection, blood poisoning and toxic shock syndrome - conditions which eventually cost him his arms, legs and other parts of his flesh.
Despite being given just a 3% chance of survival with doctors, Alex managed to pull through, but had to relearn almost every aspect of his life, including his relationship with son Sam.
Speaking to Holly Willoughby and Phillip Schofield on This Morning, he explained that after his illness, Sam would no longer kiss his altered face - a period he described as 'awful'.
'I was a stay at home father for more than two years before I fell ill. It was fantastic, we had a very close bond. Then all of a sudden you're thrust into something you don't have any control over,' he said.
'Your face is completely unrecognisable and for a little boy to look at that, having seen his father upright, legs, arms, looking normal.
'It was very hard – for the both of us – we both struggled.'
Happily, Sam has now adapted to his father's new appearance, and gives him all of the affection he wants - 'He's great now, completely fine about it. He'll give me a hug, a kiss,' he added.
Alex, who was appearing on the show with his fiancée Lucy prior to the airing of his Channel 4 documentary, The Extraordinary Case of Alex Lewis, told the pair that he now has a positive outlook, despite the challenges he's had to overcome.
'I read a book called Man's Search for Meaning by Victor Frankl, and it said you need to think about questions like "why you are here" - and the "how" will follow.'
'As I read it I thought "That really applies to my experience". Now I know my "Why?" is Lucy and Sam. And the "How?" - how I look now - that we can cope with.'
Alex and Lucy are now fundraising for a £180,000 microprocessor knee joints that will enable him to walk and play with Sam again, through their website, the Alex Lewis Trust.
'I want my son to be proud of me and at ease in his skin and with everything he does.
'You have no clue what life is going to throw at you and you have to deal with it as it comes. I don't want him to stress about the little things in life.'