Epididymitis: This condition, which is an inflammation of the epididymis (a tube at the back of the testicle that stores and carries sperm), can cause testicular swelling and pain. It can also lead to urinary symptoms if the inflammation affects the urinary tract or if there's an associated infection. The symptoms of epididymitis can sometimes be accompanied by difficulty urinating, especially if there's an associated urethral stricture or prostatitis.

Testicular Torsion: Although typically presenting with acute onset of severe pain, testicular torsion can sometimes have a more gradual onset and could potentially lead to swelling. Difficulty urinating might not be a direct symptom but could occur if the patient has an associated condition or if the pain leads to urinary retention.
Orchitis: Inflammation of one or both testicles, usually caused by bacterial or viral infections, can lead to swelling and pain. Like epididymitis, orchitis can be associated with urinary symptoms if the infection spreads or if there's an underlying condition affecting the urinary tract.
Hydrocele: A condition characterized by fluid accumulation around a testicle, leading to swelling. While it might not directly cause difficulty urinating, a large hydrocele could potentially put pressure on the urethra or bladder, leading to urinary symptoms.

Testicular Cancer: Although less common, testicular cancer can present with testicular swelling. Difficulty urinating could be a symptom if the cancer has metastasized to the lymph nodes or other areas that affect urinary function. It's crucial to not miss this diagnosis due to its potential for cure with early treatment.
Urethral Stricture: A narrowing of the urethra can cause difficulty urinating and, if associated with infection or inflammation, could lead to testicular swelling indirectly through epididymitis or orchitis.
Prostate Issues (Prostatitis, Prostate Cancer): Conditions affecting the prostate can cause difficulty urinating and, in some cases, might be associated with testicular swelling if there's an associated infection or inflammation that spreads.

Henoch-Schönlein Purpura (HSP): A form of vasculitis that can affect various parts of the body, including the testicles, leading to swelling. It's more common in children but can occur in adults. Urinary symptoms could occur if there's kidney involvement.
Filariasis: In areas where it's endemic, filariasis can cause hydrocele and, in rare cases, might be associated with urinary symptoms due to the body's reaction to the parasites.