"Pelvic gland" is not a medical term. If you have a swollen inguinal lymph node, it could be an STD even if you don't have other symptoms. See your health care provider for accurate diagnosis and treatment, as you do not appear to be qualified to diagnose yourself.
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.
It can cause infertility, but it can also cause your death. A untreated twisted testicle, aside from being incredibly painful, will swell and die. Keeping a dead testicle inside your body will do more harm than good.