Hi don't be scared? I presume you are a young student. Did you have any injury e.g. playing hockey? How many ribs are affected and right, left or bilateral? Any pain?
How long has this been so, and did it appear gradually or suddenly? Any redness on your chest or back [ask someone to look [for back]]?
If it is a large swelling OR there are many lumps OR if it is painful [particularly if it is made worse by coughing/breathing], seek advice from your doctor [in the current crisis, it will probs have to be a video consultation].
Relax though - chances are, in a young person, it is a soft tissue inflammation problem.
M