Hi ! Possibly you have got a vericocele ( dilated veins) of the testis on the left side, which is common on that side. The cause for this could be ideopathic, or due to prolonged standing. The radiation
of the pain to the buttock may or may not be inter related. The treatment for vericose veins is surgery if need be. Vericose veins are said to cause sterility
, and so your doctor may advise you to go for a semen analysis
before deciding on any course of action. In the mean time you may go for a good scrotal support, and some anti inflammatory drugs for relieving your discomfort due to this. Wishing you an early recovery.