I found a painless lump on my left testicle and I’m freaking out. What to do?

It's understandable to be worried about finding a lump on your testicle, but it's important to stay calm and seek medical attention. The lump you described could be caused by a variety of conditions, including:

Epididymal cyst: These are fluid-filled sacs that develop in the epididymis, a coiled tube located behind each testicle. Epididymal cysts are usually painless and harmless, and they don't require treatment unless they cause discomfort.
Hydrocele: This is a collection of fluid in the scrotum that can cause swelling and discomfort. Hydroceles can be caused by injury, infection, or other factors.
Varicocele: This is a swelling of the veins that drain the testicle. Varicoceles can cause discomfort and infertility in some cases.
Testicular torsion: This is a medical emergency that occurs when the spermatic cord twists and cuts off blood flow to the testicle. Testicular torsion can cause severe pain and swelling and requires immediate medical attention.

It's recommended that you schedule an appointment with your urologist to determine the cause of the lump and receive appropriate treatment if necessary. Remember that early detection and treatment can make a significant difference in the outcome of any potential medical issue.