Hi Miss,
You have sensitivity to sweet and cold due to the cavity (caries) in your tooth. Due to caries, the Enamel & Dentin layers of tooth gets dissolved/infected/affected and whatever you eat/drink, comes into direct contact with dentin layer or pulp of the tooth.
If the sensitivity lasts only for few seconds, there are chances it can be restored (filled) and you problem will be resolved.
But, if sensitivity persists for longer duration, you might have to go for Root Canal Treatment of your tooth.
Next Steps
Consult a good dentist at his clinic. X-Ray of your tooth will devise proper treatment plan suited for you.