Best thing I can suggest for you right now is to take your dog to the veterinarian, and soon!
Puppies and young adult dogs are notorious for eating things they shouldn't, and those things (socks, rocks, balls, toys, clothing, towels, etc...) can cause
intestinalAmebic liver abscess
Barium enema
Colorectal polyps
Colostomy
Gastrointestinal bleeding
Gastrointestinal disorders - resources
Gastrointestinal perforation
Intestinal gas
Intestinal leiomyoma
Intestinal obstruction
Intestinal obstruction repair obstructions, which can, in turn, cause serious illness or even
deathDiscussing death with children
Gangrene
Liver cell death
Loss of a child - resources
Sudden infant death syndrome if left untreated. Of course, you might be dealing with something far more
benignBenign ear cyst or tumor
Benign positional vertigo like just an upset stomach or
intestinalAmebic liver abscess
Barium enema
Colorectal polyps
Colostomy
Gastrointestinal bleeding
Gastrointestinal disorders - resources
Gastrointestinal perforation
Intestinal gas
Intestinal leiomyoma
Intestinal obstruction
Intestinal obstruction repair parasites, but since your young dog is exhibiting signs of serious discomfort, better
safeSafe driving for teens
Safe sex than sorry!
IntestinalAmebic liver abscess
Barium enema
Colorectal polyps
Colostomy
Gastrointestinal bleeding
Gastrointestinal disorders - resources
Gastrointestinal perforation
Intestinal gas
Intestinal leiomyoma
Intestinal obstruction
Intestinal obstruction repair obstruction and intestinal foreign bodies can often be diagnosed with an xray, but not always. Some things, like wood chips for example, aren't visible on a plain films and may require some other testing, such as a barium series, to diagnose. Surgical removal of the offending object is often necessary, but if diagnosed and treated quickly, most dogs will recover well.
Of course, other possibilities include intestinal parasites, gastritis/enteritis, or dietary indescretion, so routine bloodwork and a stool sample may be in order as well. Bottom line is your vet can help you get to the bottom of it, and hopefully, get your guy some relief soon!
Good luck!