In the case of dyschezia (pain with bowel movements) and dysuria (pain with urination), these symptoms can actually provide some accurate info about your condition.
If you have any of these two symptoms you have now narrowed down the location of your lesions, as these are the only things that can cause this type of pain. Peritoneal lesions, ovarian cysts and rectovaginal endometriosis can all characterize this type of pain.
It typically occurs due to the proximity to the intestine or from bowel infiltration. The pain that is derived from there comes from cyclical inflammation in the localized area. Based on specific inflammatory markers such as prostaglandins, cramp-like pains before bowel movements can and are experienced throughout the painful phase of the cycle.
Other symptoms are stool irregularities and, if the colon has been deeply infiltrated and distended, continual obstructions. Full penetration of a lesion to the intestinal wall is referred to as hematochezia, in which stools can then cyclically become bloody. Due to the lesions' locations, and their hormonal nature, the estrogenic cycle that applies to inflammation is derived here.
The lesions constant and erratic shifts of estrogen levels directly affect intestinal motility through the direct interaction of CCK receptors in intestinal cells. CCK receptors are directly involved in the movement (peristalsis) of the intestinal tract. Over and under stimulation can cause hyper or hypo peristalsis, or as you have come to know it, pain with bowel movements.
The inflammatory cascade then results in hyperinnervation of the lesion which will then result in heightened pain when pressure is applied. Usually, this cycle follows as constipation then diarrhea then normal bowel movements, repeating, accompanied by acyclical pain.
Due to their location, dyspareunia (painful intercourse) is a common side symptom. For those that suffer from painful urination (dysuria), the same concepts apply here. The results are frequent urination or feeling like you didn't fully empty your bladder (pollakiuria), and painful urination. If your lesions have fully infiltrated your bladder or urethra then hematuria (blood in urine) is seen.
It truly is that simple, however, as time progresses these symptoms become worse for two reasons. Endometriotic growth and Spinal Hyperalgesia coupled with Central Sensitization. This is, the rewiring of the nervous system to experience heightened senses of pain.
This means that pain tolerance is not a factor anymore because it keeps changing. To explain this in a nutshell: Pain is a physiological warning signal, as a result when pain is ignored it often tends to increase, again, this is due to its interpretation as a warning signal, meaning the body wants to run away from the danger.
If this pain is not treated, reduced or it repeats consistently, the body classifies the pain as threatening and rather than reducing the signal, it increases it at the spinal level through erratic neurotransmitter signaling.
This then further augments your pain as the smooth muscles, seen in the bladder, GI tract and uterus contract even further.
As you can see, this, much like endometriosis, is a cycle that feeds off of each other, further creating worse and worse symptoms.