Then she began to suffer from loss of balance, vertigo, deteriorating eyesight and severe bouts of sickness. She was forced to quit her job as a part-time sociology lecturer at University College, Worcester.
In 1992, almost two years after the first symptoms appeared, doctors confirmed she was suffering from multiple sclerosis (MS).
At that time, Mrs Parkinson, who has two children, had ambitions to study for a PhD and become a full-time lecturer, but the crippling illness began totally to dominate her life.
"I just slowed down and it was quite dangerous for me to be at home alone because I would fall over," said Mrs Parkinson, 43, of Bredenbury, near Hereford.
"One of the most frightening things is that you choke quite a lot. I also had total body cramp - it was so painful, the doctor gave me morphine."
Doctors gave Mrs Parkinson steroids to relieve the symptoms, but refused to prescribe the more effective, but more expensive, beta-interferon treatment.
So 13 months ago, Mrs Parkinson and her husband, David, who owns an electrical transformer company, decided they would pay the pounds 10,000-a-year cost of the drug Avonex.
She is one of more than 70 MS sufferers being treated at Queen Elizabeth Hospital, in Birmingham, but the local National Health Service trust can afford to prescribe the drug for only 44 patients.
The trust could save more than pounds 70,000 if it accepted "parallel imports" of Avonex from Italy, allowing them to offer the drug to more patients. It is thought that Mrs Parkinson is now near the top of the waiting list.
The couple have no savings and they have had to shelve plans to move from their two-bedroom bungalow into a larger house. The drug is brought to their home by courier van once a week and Mr Parkinson administers it by injecting his wife in the thigh.
One month after Mrs Parkinson began taking the drug, she began to feel better and she has experienced fewer severe attacks. She has now started studying for her PhD in English.
"For the first time there is hope and I don't feel MS is the dominating force in my life," Mrs Parkinson said.
"I have more energy. The drug is not a cure but it's keeping the disease at bay and giving me hope, which is very important.
"It's changed my life. I feel happier and more at ease with myself. I still have some of the disability, but I couldn't possibly have done the PhD without the drug.
"I feel annoyed that the majority of people don't have access to the drug and that it's rationed because of cost. It is the duty of central government to pay for this drug to be more widely available. They have a duty to provide it for MS sufferers, but at present it's like a lottery," she said.Reuse content