Hello! Thank you for the query. Such symptoms most likely indicate inguinal hernia which has reached scrotum. As you do use fiber rich products, I assume that you have constipation problem. Hard pushing on stool can cause such hernia. So is heavy objects lifting or even coughing. Other possible reason of such large testicle is hydrocele, spermatocele. Testis cancer is possible however it is quite rare. You can put the flashlight into this enlarged testis, if it passes the light freely, the cyst it is. If not, hernia is most probable. Your abdomen has gotten bigger because intestines are probably in your scrotum what impedes stool passage. In such situation you should be aware of abdominal pain, gas or stool blockage, vomiting. If any of this symptoms will appear, it ca indicate urgent condition (bowels obstruction). You should visit general surgeon for the diagnose and if hernia will be confirmed, surgery is necessary. Hope this will help. Regards.