My husband has been complaining of pain deep inside the abdomen to the left of his belly button for the past few weeks. It is fairly persistent, is usually dull but nagging.
We thought it was linked to digestion but the digestion meds given to him are not making any difference to it.
I am wondering if it could be linked to the prostate cancer?
Before radiation treatment, I had dull pain to the far left side of the lower abdomen, which turned out to be seminal vesicle involvement, where the tumor had probably blocked the vas deferens. A color-Doppler ultrasound and MRI confirmed +SV. The discomfort went away after treatment.
Consider consulting with your primary doctor since it could be many things. If he has diverticuli in the colon he may have diverticulitis and he needs antibiotic treatment.
if the prostate cancer had reached the spine then it is a possiblity, my father had complained of abdominal and back pain few months ago that prompted the uro dr to request a bone scan, this showed his pca had reached the spine
Kidney Stone?
I think our minds jump to prostate cancer whenever something happens to our health..Yes this could be prostate cancer but it could also be many other things . Something as simple as constipation could cause pain in this area. Go to your primary care doctor and have them look.
UTI - urinary tract infection can be checked by primary care doctor or urologist.
What you are describing sounds to me like it may be Diverticulitis. I have had this condition for at least 20 years. It is usually treated with anti biotic.
I concur with the Diverticulitis comments. I've been dealing with that for decades. I even noticed on some test results where it was mentioned. Have you gone through test results to see if it has been noted?
Pain related to xgeva? 
Cancer and stress: not directly related to prostate cancer but interesting research
Prostate cancer and pain
Prostate Cancer - Pain
Bone Pain from Prostate Cancer 
