The presence of blood in the stool is a worrisome finding and you should seek out consultation with your primary care doctor
. There are many different causes of bloody stools, some of which are very benign and some of which are more serious and need to be addressed. In any case, it would be extremely rare for any bloody stool to be related to one's rib cage, especially in the absence of any trauma or severe abdominal pain that could suggest a perforation of the bowel.
Bloody stool in the setting of recent constipation could be due to an ulcer that has formed due to the hard stool rubbing up against the lining of the intestine. Along the same lines, it is possible that the constipation led to the transient rupture of an internal or external hemorrhoid, which can certainly lead to bright red blood in the stool and on the toilet paper. Other causes of bloody diarrhea
include bacterial infections, such as with certain strains of E. coli, as well as underlying diseases like ulcerative colitis
. As the cause of your bloody diarrhea is not completely clear, it is strongly recommended that you seek out consultation with your primary care provider for further work-up.