But as the pain only worsened, Clunies-Ross said he knew something wasn't right and was driven to the Prince of Wales Hospital by his girlfriend.
"I woke up in the morning and was really, really crook. Sweating, shivering, started throwing up," he said. "I tried to get up and fell over. I couldn't stand up.
"It's pretty blurry from there. I remember lying on the floor in the emergency department while my missus tried to explain to them I was unwell.
"I can't remember much, a doctor seeing me and unwrapping all the dressings from the night before. I told someone I thought I had spiders on me so I was pretty out of it. I was operated on that night."
It was quickly discovered that a nasty bug called 'necrotising fasciitis' had started to eat its way through Clunies-Ross's healthy leg tissue.
Although surgeons worked quickly to clean out the dying tissue in Clunies-Ross's leg, the infection, which claims the lives of one in four people who encounter it, kept spreading.
"Someone told me it spreads at four centimetres an hour," Clunies-Ross said. "I was pretty out of it but the look on my mum and dad's and my girlfriend's faces told me it was serious."
With the help of infectious disease specialists and multiple surgeries, though, Clunies-Ross is now on the road to recovery.
Missing the rest of the season was a tough pill to swallow for the rising star who hoped this year would be his chance to prove himself in the Top 14 and Aussie Sevens program.
But Clunies-Ross counts himself lucky after the rare medical scare and said the set back would only give him the determination to come back stronger.
"I didn't realise how realistic a scenario an amputation was but [the medical staff] were all like 'wow, we saved it,'" he said.
"I'll put up with the scar I guess."
