Thanks everyone for the replies! Very much appreciated!

I went back to the GP last Friday, and between the things we talked about was my bladder issue. She instantly connected the problem with my lower back, which has been swollen since the accident (nightnurse30, spot on!). The GP did a physical examination and said that it's likely that the issue will resolve itself once the swollen area go down. She also checked my ankles and said that I'm not retaining liquids, so basically her advice was to keep doing whatever I'm doing (going to the bathroom 4x a day -before take my meds so I don't forget - and force it out) but to keep an eye and if anything gets worse or in the sign of water retention, I should go back and the nurse will do the bladder scan... Worse case scenario would require me learning self catheterisation (REALLY don't want this to happen, so I'm here praying for the lower back to get better too).

I also have another 2 areas of my spine swollen, one is the back of the head until shoulders, because I twisted the neck between the 2 head impacts, and the other is in the mid section, ribcage, where I got a broken rib... I'm having so much painkillers that it's easy to forget how much is wrong and the other places that would also hurt a lot, besides the headaches.

Andromeda: sorry to hear you also are having problems with your bladder. Did you also hurt your lower back in your accident?! You should talk to your GP about it, if you are taking strong painkillers, you could be missing some kidney pain that could become something serious if not treated soon. Take care of yourself.