The student had a persistent rash on her thighs, which spread to the rest of her legs last Sunday night.
The itch became so painful and unbearable that 18-year-old Maria Schooling decided to go to the doctor at about 11pm.
She took a taxi to a nearby clinic about 10 minutes away from her home and hobbled in at about 11.15pm.
But she got a rude shock when she was turned away after she told the clinic assistant that she had only $50 cash with her.
Miss Schooling told The New Paper on Tuesday: "I was pretty desperate to see a doctor because both my legs were affected. They were swollen and had pus and bumps all over. All I wanted was some relief cream."
Before that, the clinic assistant warned her that the bills would be "expensive", citing a consultation fee of $47.
The incident happened at Kao and Tan Family Medical Centre and Surgery at Jalan Membina, opposite Tiong Bahru MRT station.
It was the nearest clinic available at that hour for Miss Schooling, who lives at Telok Blangah Rise.
A partner of the clinic, Dr Tan Teck Jack, has since apologised for the incident. He said that the stand-in doctor on duty that night was not aware of the situation.
The clinic assistant has since been suspended pending the clinic's investigation.
Miss Schooling said that she had tried to get enough money by making a few harried phone calls.
When she finally had enough at 11.45pm, she said she was turned away again - the clinic assistant told her firmly that the clinic, which runs from 7am to midnight, was closed for registration.
Miss Schooling, who was accompanied by a friend, Miss Alison Sin, was infuriated that the clinic assistant did not inform them of this earlier.
The women had remained in the clinic till 11.30pm while they called their friends and relatives for help to transfer money into their accounts and only left the clinic to withdraw money from a nearby ATM.
Miss Sin, 24, a freelance in-line skating instructor, said: "It felt like she did not see the point of entertaining us because we were kids and all she thought about was the money. We kept saying that this is urgent, but she did not even ask us what was wrong."
Earlier, Miss Schooling had also asked if she could leave her identification card with the clinic and her mother, who was working the night shift, would return the next morning with more money.
She even asked the assistant to speak to her mother over the phone.
Both requests were turned down.
Her mother, Mrs Angela Schooling, a printing foreman, said: "I couldn't do the transfer (of money) because it was a peak period at work at the time.
"It infuriated me that she refused to talk to me over the phone and when I called the clinic, no one picked up."
Eventually, the teenager returned home and resorted to iced towels and cold showers to ease the itch. She could see the doctor only two days later because she had difficulty walking initially.
On Wednesday, Miss Schooling, accompanied by her mother, went to the same clinic. The bill came up to $82 for three types of oral medication and steroid creams.
The doctor said it was an infection, and her itch was aggravated by eczema. Miss Schooling said: "If I had seen the doctor earlier, I wouldn't have scratched so much and it wouldn't have spread or there wouldn't be scars now. "What if someone had been in a more serious situation than me?"