I understand your worry.
There are several possible causes of a lump on a testicle. It is common to have a collection of fluid, such as a hydrocele, spermatocele, vesicocele, or hematocele or cyst within the epididymis
many spermatoceles or cysts that do not cause symptoms do not require specific treatment. If a persistent spermatocele or cyst is larger or causes persistent pain, then it may require surgery.
Ultimately, it would require an appropriate evaluation to determine the exact cause, but none of these problems require an urgent evaluation.
Tests may also include a physical examination and colour doppler ultrasound study of testes.
You should consult a urologist for a clinical examination
The only condition that would require an urgent evaluation would be torsion (twisting) of the testicle, which usually causes significant pain, but can also cause swelling, although usually not a small separate lump.
Until you can be seen, it may help to apply cold compresses to help ease the swelling and to relieve tension on the scrotum, such as by wearing an athletic supporter.
It is not likely to be testicular cancer, as the other problems are more common.
Hope this helps.
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