Why Is My Guinea Pig Swollen On His Private Parts And Is Having Trouble Use The Bathroom?

This could be from trauma, a mass, or an infection among other issues.  This guinea pig needs to be examined by a veterinarian.  Inability to urinate is a life threatening emergency and if this swelling progresses your guinea pig will become unable to urinate.

Bladder infection or its probably stomach or gut sicknesses

No my guinea pig private is swollen is that normal