Hi. Thanks for your query. History noted. You are a young boy of 24 and noticed discomfort in left testicle - for no obvious reason you can think of; the discomfort is off and on- not much of an erection. The probable causes are: as per the history you have provided::: *The first probable reason I can think about is varicocele - this is because you have major discomfort; no obvious cause and the varicocele is most common on the left side only. *Epididymo-Orchitis, meaning inflammation of the testis and the epididymis. There may not be any obvious reason in every case. * Trauma - a trivial trauma which a person forgets easily- rare *obstructed hernia on the same side- at you age there can be an indirect type of hernia which cause case the similar symptoms. This is best diagnosed on physical/ clinical examination by a General Surgeon or an Urologist and an ultrasonography and color doppler study. Once the diagnosis is made, it is easy to plan for a treatment. Start giving a support to the scrotum. Drink plenty of water orally., Consult an urologist.