continous twiching pain near the anal end

[ASV]

I had undergone surgery for CANCER RECTUM and i have COLOSTOMY for the last 5 years.I was subjected to ACUTE MYOCARDIAL INFARCTION ON OPERATION TABLE. Then after 2 years i was also operated for CANCER : LEFT ILIAC LYMPH NODE.Then i underwent complete chemotherapy.After both operations i had DVT in both legs.After chemo i had a massiva fall in the bathroom.The MRI screening show:
             "The L4-5 intervertebral discs remains low in     intensity on T2W1 signifying degeneration.The posterior central  protrusion of L4-5 disc is unchanged .It is still causing indentation of the thecal sac and compresion of the contained nerve roos.No other disc bulge is noted."

Ihave severe pain in the anal end region like nerve twiching due to which i am unable to Sit ,Walk, Sleep or do anything.
This pain prolongs for 10 to 15 hours once a week which is not reduced by any painkiller.
But it reduces a little by low back exercises.
               Lastly in Arpil 2007 i had undergone surgery for enlarged prostate because i has urine retaintion of 235cc in the bladder.
So what do recomend me to get a quick relief.

                -- thanking you.