I can understand your concern for the bump in your right knee. People who skate often come with such problems. It can be a lump ( as it disappears when leg is straightened ) or a cyst
. It can also be due to the inflammation of tissues, tendons or nerves. You will have to get it examined clinically by a doctor so that diagnosis can be made.
It can be examined if there is fluid in the lump, biopsy
can be done and sample sent for histopathological examination. If reports are fine it can be removed and you will get relief shortly. But if it is a bony projection or a growth, you will need to go through more investigations and X-Rays before management and treatment ca be started.
To avoid bumps use well fitting skates, wear properly fitting shoes, protective paddings should be used. Injuries should not be neglected and consultation with doctors should be done to avoid complications later. Take care.