Hello Practo User,
Your problem is called as a Ganglion.
It happens due to fluid collection in the local tissue.
It increases with activities and decreases with rest.
There is no medicine to reduce it.
Surgery is only option.
But if it is not troublesome ,there is no cause for worry.
Next Steps
You can consult me online through Practo,if you want to discuss further details.
Regards.