I highly recommend that you go to see your primary care doctor
or your OB GYN doctor about this issue as soon as possible. In someone your age, it is very unlikely that your breast is sore because of cancer or another very serious medical problem, but it is important to get this ruled out so that you can have some peace of mind.
Your doctor will carefully examine your breasts, looking for any evidence of a lump, cyst, or other concerning area. Most of the time, in young women, if a lump is found, it tends to be a benign (non cancerous) area of the breast. Depending on the characteristics of your pain and the physical examination, your doctor will determine if any identified problem area can be simply observed for a while to see if it changes, or if it needs to be worked up right away.
If your doctor decides to work up any problem areas, they will typically start with a radiologic study, such as a mammogram
or a breast ultrasound
. Based on the results of these studies, it is sometimes necessary to biopsy the problem area, often simply by inserting a needle into it.
Go see your doctor right away!