testicle ache

Hi, I'm 26 and I keep healthy and in good shape. Over the last month I have developed an achey (achy) pain feeling in my left testicle. Firstly I was born with an undescended left testicle but had the operation to correct it so no problem there. However, recently whilst checking myself I find that my left testicle has lots of veins around it, more so than my right which is perfectly normal. I have recently checked the actual testicle for pain, but the discomfort seems to be coming from a vein or something located just above my testicle. This achey (achy) feeling comes and goes, its not major pain just an ache that gives me a sense of heaviness in my left testicle when sitting and standing. I also get similar aches and pains down my left leg also again not major, but I am aware of it. Not too sure if this relates to my sciatica as I slipped a disc last year and do get regular sensations from that. I'm worried about this achey (achy) feeling in my left testicle, its not swollen and hasnt changed shape or size, but Im becoming a nervous wreck as to what it is. I went to a sexual health clinic and had a urine test and blood test and they have come back all clear so what now? Do I need a scan, is it serious, does it affect fertility, what could it be? I'm living with it at the moment but its causing some discomfort. I would appreciate any help, thanks