The virus responsible for chicken pox
spreads through air when patient with chicken pox coughs or sneezes. It can also spread from the vesicle by touching the fluid .
But the really bad part is the girl in next room had been spreading the virus through coughs and sneezes 3 days before the rash appeared and you knew she was having chickenpox
So probably you are already exposed to virus
It usually takes around 2 weeks for the rash to appear after exposure.
Preventive measures after exposure are not 100 % effective , but they may reduce the severity.
You can get varicella vaccination
and it may prevent or make the disease less severe.
You can take acyclovir
as soon as you notice first vesicle and the disease is cured in few days.
Another approach is to take acyclovir tablets 4 times a day for 7 days starting from 7 day after exposure. it provides around 80% protection.
Varicella immunoglobulin is also available for preventionConsult dermatologist
or physician near to you
If you are not already exposed , avoid exposure by staying away from the patient, not going to her room , not to share bathrooms , not to share towels ,bedsheets etc