Dear friend, welcome and thanks for entrusting your query here at HCM!
I am Dr. Prasad Akole (Critical Care Expert- http://bit.ly/Dr-Prasad-Akole) and am glad to address to your query here.
is most probably swollen due to trauma or bleeding in the sac.
Is it discoloured bluish black?
You should seek immediate surgical consult in an ER. If testis is traumatised, waste of time can cause serious problems.
Take simple paracetamol
if available at home for pain and use cloth/ underwear support for the enlarged scrotal sac to hold it up and reduce pain.
I hope you are fully satisfied with the guidance I gave.
I would be glad to answer any further queries. Please ask for any clarifications before closing and rating this answer.keep me posted on the progress.
Thank you and Good luck!