IBS symptoms and seromas

I am a young female, 26 years old.  I have been suffering with IBS for roughly 5 - 6 years on and off.  It reached a peak about 2 years ago and had me sick on almost a daily basis for about a year and a half before I decided to see a dietician to change my diet.  That has helped a huge amount, however I still suffer from symptoms from time to time of diarrhoea, constipation, bloating, pain, etc.  On top of that, I also had an inguinal hernia that formed about 5 years ago too.  I assume the hernia formed as a result of straining when going to the toilet from the IBS possibly.  I had the hernia repaired 4 months ago and now have a large seroma that has been aspirated 3 times and now requires surgery to permanently fix.  Needless to say I have been through a lot!!!  I have had 2 ultrasounds and one CT scan of whole abdominal area - doctors say nothing sinister going on.
On top of the usual IBS symptoms I also experience internal pain after defecating, which then moves up and across my lower abdomen.  It is a dull, aching pain, sometimes alleviated by urinating, but builds up again with time.  Also sometimes feels like I have really bad indigestion, which sometimes gets worse or better with eating.  The pain is often followed by a period of constipation.  My seroma also seems to increase in size during these painful times.
I have had these symptoms before and after the hernia repair.  The dull ache improves once my bowel movements return to normal.
What i want to know is:  1.  are these symptoms just related to the IBS flair ups?  2.  can a seroma be present before surgery and can the serous fluid moving around the body be causing some of the pain I feel and hence why the lump on the skin is bigger after the pain.  3.  would a CT scan show if there was something else happening that could be causing the pain?
I appreciate any information forthcoming that could assist me.  I have been seeing my surgeon regularly.  He will perform the drain of the seroma in a few weeks and I am hoping he can tell me where the serous fluid is coming from and fix the problem permanently.
Thanx

[boron]

Rectum and bladder lie one beside another, so when you defecate, bladder moves a bit. It is possible there is something on the outher side of the rectum or bladder what moves and causes the pain.

It is not recommended to have more CTs of abdomen at your age, if anything, it should be an MRI. But surgeon should say what MRI can show and what it can miss. One possible investigation before surgery is laparoscopy - a doctor can see the outer side of abdominal organs directly. If you have one seroma, you can have more of them, which were not detected by ultrasound or CT. It's also possible that some fibrous tissue (adhesions) has overgrown between certain organs and pull them and cause pain as they move. This should be also seen during laparoscopy.