What causes it, is you getting contaminated by your niece coughing, she will have got it from some who sneezed or coughed. These virus bugs are very contagious.
It is highly likely to be a virus and you need to stay warm, drink plenty of fluids, hot water with fresh lemon juice and honey is good. Take pain relief medication as directed on the packet to get your fever down.
If you like honey, have some honey to help ease the sore throat and the cough. Coughing is the body's natural response to getting rid of an irritant. In this case, the irritant is the virus.
When we are exposed to viruses and our immune system is low, then we get it.
You can do steam inhalations. To do a steam inhalation, boil up a kettleful of water and pour this into a bowl, taking care not to get scalded. Put some Vick or olbas oil or a few drops of menthol oil into the water. Bend your head over the bowl and cover your head and the bowl with a towel. Breathe in the steam through your nose and out through your mouth for a duration of 10 minutes. Do this 4 times a day if you can.
You can also rub Vick on to your chest, back and throat.
You can gargle with salty water to ease the sore throat.
Clear chicken soup is very good for this type of illness.
If your condition worsens, any of you have difficulty with breathing, or produce green mucus or any blood stained mucus, contact your doctor.
With the seasons and the weather changing, there is a lot of it about - even in the UK.
Wishing you a speedy recovery.
I have had it for months so have other family members, our opinion now is it is environmental caused by the toxins they are spraying upon us,watch 'What on Earth are they Spraying' every day where I live we see the trails from the spraying across the sky, many are sick .
That ain't good.
As you are concerned about those spraying trails, and it will carry in the wind and cause problems to those being exposed to the chemical, contact your Environmental Health department so that they can monitor the risk to human and animal health.
If you have an authority that is higher in status that your Environmental Department contact them.
In the UK with have the Ministry of Agriculture, Fisheries and Food.
In the US, there are some foods that are sold to the public that have chemicals in them that are banned in other countries because of health risks. Check your food and drinks labels.