What Causes Sluggish Bowel Movement After Removal Of Kidney?

My right kidney was surgically removed early Sept 14. I m still recuperating & recovering. I am hypertensive and am on drugs. I have a bowel movement issue, it is sluggish and my motion is weak and unsatisfactory. Local doc prescribed Veloz D; have taken for two days so far and my stomach is gassy and gave me a constant dull pain. Night sleep was disturbed. I browsed the Internet where I found that Veloz D has Genitourinary side effect. Will this impact on me? I am 73+, male.