Scrotal swelling in 7 year old

Hello @kars123. Welcome to Mayo Clinic Connect.

While we wait for others to join this conversation- here is some information you might find helpful from Mayo Clinic.org https://www.mayoclinic.org/symptoms/testicle-pain/basics/causes/sym-20050942

Is your son in pain with this? what other symptoms has he had?

At first he used to say it hurts a bit when he pressed hard on it. He maintains to be active and does not complain of pain otherwise.

Hi @kars123,

Since you mentioned that, "...the doctor believes the fluid sack is separate from the testis, which makes him think it is NOT a hydrocele," I thought you might be interested in reading this information about a benign condition known as spermatocele:
https://www.mayoclinic.org/diseases-conditions/spermatocele/symptoms-causes/syc-20377829
I hope your son is doing well; were you able to find out a cause for the scrotal swelling?

Due to the young age I doubt that it would be a spermatocele. I think it still could be a hydrocele or fluid through a defect in abdominal wall that could lead to inguinal hernia- where intestine could protrude. Again, I’m not an expert. My son had similar at same age- more tender though. He saw a urologist who diagnosed it as epididymitis.