On the first occasion, Stuart Hutchison, 19, was told he had an ear infection. On the second, two years later, he was told a lump was nothing more than a cyst.
But on both occasions, the doctors were wrong and Stuart actually had brain tumours.
Officials are investigating after the teenager lodged a complaint against his local health board.
Stuart told his local paper: "It's shocking. I feel let down by the doctors. I don't want this to happen to anybody else."
When his first tumour was finally diagnosed, surgeons told his family that so much pressure had built up in his brain that he would have been dead in 24 hours without treatment.
The student from Clackmannan, Scotland, began suffering severe headaches and dizzy spells in May 2011.
He went to a healthcare centre five times in a month. Doctors said his condition was down to stress, viruses and even blamed labyrinthitis - an inner ear infection that affects balance.
But his condition continued to deteriorate and by July that year he was barely able to walk, had slurred speech and couldn't use his right arm.
The family called a GP to visit Stuart at home but the doctor never appeared, so worried mum Fiona and dad George took their son to the accident and emergency unit at Stirling Royal Infirmary.
A scan revealed Stuart had a massive brain tumour which could have killed him. Fiona, 46, said: "They discovered there was a huge mass on the back of Stuart's brain.
"The doctors said that if he hadn't come back that morning and been dealt with there and then, he would've died in his sleep. The pressure on his brain was so massive it would have happened within a day or so."
After two life-saving operations on the cancerous tumour, 33 sessions of radiotherapy and months of being fed through a tube, Stuart was on the road to recovery.
But in January, he faced more agony when he discovered a fresh lump near his brain surgery scar.
Despite explaining his illness and treatment, an A&E doctor told Stuart that the two-inch growth was 'just a cyst'.
Unconvinced, the teen sought a second opinion from surgeons at Edinburgh's Western General and was told it was another tumour.
Last Thursday, he had the growth removed, leaving a huge scar on the back of his head.
He is waiting for test results next week to find out if he needs further treatment.
Stuart is furious at the way his illness was handled by GPs and the A&E doctor's failure to spot the second tumour. He has now made an official complaint to the health authority, NHS Forth Valley, who are responsible for the hospital and the healthcare centre.
NHS Forth Valley said they had launched a probe into Stuart's case.
A spokeswoman said: "We have begun a full investigation into the concerns raised and have been in contact with the family to offer to meet with them and give them any support they may require."