I don't actually work in medicine, but due to my circumstances (carer) - I'm quite familiar with them all and have picked up a thing or five along the way
The morphine is the best for pain, but it is also the most addictive and there is a chance of not only tolerance, but also of dependence. However tolerance does take a while to develop (ie Prolonged usage). For the relatively short term which you are taking them, you should be fine in that regard.
If pain persists, I'd opt for the Tramadol over the morphine if its 'effective' enough in relieving the pain. Tramadol is also used in the treatment of 'weening' off opiates like Morphine, so if you are still taking the morphine - save a few Tramadols when the morphine runs out. (it will ease the 'discomfort and side effects' of going from using opiates to not using them)
Valium tolerance can happen quite quickly, so use as sparingly as possible. Obviously your Doctor will give you the best advice for your situation.
Enjoy your last day of sick leave. It won't take long to not miss work so much