Could be testicular cancer. See a doctor for a screening as soon as you can. Just like a lump in a female's breast a lump on your testical (nut) MAY be a sign of testicular cancer, however, you may be too young for that. See a doctor and get a screening of your testicals done IMMEDIATELY. As with most cancers, the ones that survive the most are the ones that catch it early.
There are many possible reasons for a lump on your testicle. You should see a doctor as soon as possible. See the link below.
a testicle
The most common symptom of testicular cancer is a painless lump or swelling in the testicle.
Some testicle problems, like infections and swelling, are treated with antibiotics like Vibrox. See the link below.
Testicular Cancer. I am an RN nurse. This is how I know.
Any lumps on your testicles should be taken to a doctor. See the link below.
It is probably the vein
You need to go and see a medical doctor about this as soon as possible. See the link below.
If one testicle is bigger that is definitely not a problem. Most body parts aren't perfectly symmetrical. If there is a lump in the testicle or it feels abnormal or liek it has grown I would see a doctor.
Dude go to your doctor.
It is normal for one testicle to be a little bit bigger than the other. This is no problem. If one is much bigger, or feels swollen, or has a lump on it, then you should see a doctor as soon as possible. See Related Links below.
If it's a firm lump behind your left testicle, it's cancer. If it's not, it's nothing. Your testes should be relatively firm with some give. Each testicle will be a slightly different shape or size and this applies to firmness too. However, if you still have any concerns, see a doctor.