It sounds like you've been given a reasonable prescription on discharge with codeine and oral paracetamol, if you're not managing though I'd look to your GP to review and consider whether anything should be altered. NSAID use can have some nasty side effects on your kidneys and stomach in particular so this might be why they've stopped it. i.e. it's better to be in pain over a short period then to cause a kidney injury or ulcer resulting in more significant longer term problems. Your GP maybe able to advise that it's ok to restart/put appropriate monitoring
There are lots of factors that affect how we experience pain, whilst effective analgesia is important our outlook on therapy and mood can be just if not more important. For instance there's absolutely no difference between oral and IV paracetamol in terms of how it actually relieves pain, it's the same drug and doesn't work in minutes in either instance it works over hours, from cumulative dosing which safely get you to the therapeutic dosing level which you don't reach from a single dose. There is a big psychological difference in seeing a clinician putting up a drug that runs into your vein directly or taking a tablet that you're well aware could be picked up in Morrisons. That you felt such a high level of relief in minutes is clear evidence that this came from within you, not the paracetamol.
I work as a paramedic as see this routinely, patients in severe pain sink back and relax after pushing the flush quickly reporting how much better their pain is already, when all I've given at that point is salty water. The power of the mind in getting control over pain is huge. (This isn't me trying to trick anyone which wouldn't be ethical; after placing a cannula you flush it with water to help confirm it's in the correct position and so there's no blood left in the cannula that will clot and stop it working).
There have been some really good studies between oral and IV paracetamol in patients with moderate to severe pain and there was no difference between them in terms of how they relieved the pain - patients were given trial packs with tablet and iv solution, the paracetamol was in only one and neither the doctor or patient know which, the studies looked at the patients perception of their pain and there was no difference between them.
One of the studies posted in the british medical journal:
Conclusions Overall, there was a small but clinically significant decrease in pain in each group. No superiority was demonstrated in this trial with intravenous paracetamol compared with oral paracetamol in terms of efficacy of analgesia and no difference in length of stay, patient satisfaction, need for rescue analgesia or side effects.
(https://emj.bmj.com/content/35/3/179)