Hi, welcome to the ehealth forum and I am glad to help you.
In general, lymph nodes become swollen when they are active either due to an infection, inflammation, or cancer. Minor infections can lead to the enlargement of lymph nodes in the neck and groin but those less than 1.5 cm and 2 cm respectively in size are insignificant clinically. And these can stay so for many years and these are not of serious concern.
Your doctor would like to examine the lymph nodes by feeling them and characterize their nature, size and consistency and id required order further investigations such as CBC, chest X-ray and fine needle aspiration cytology etc. And the same is not be possible online.
Hope this helps. Take care.
Note: This post is not to emphasise final diagnosis as the same cannot be made online and is aimed just to provide medical information and no treatment suggested above be taken without face to face consultation with health care professional.