Thank you so much for answering my questions so quickly. I'm going to start as of today and I'm really confident I'll be able to kick this habit once and for all.
You are addicted to the codeine that is in the Nurofen Plus. It is not a strong opiate and you should be able to taper yourself if you really want to. You have to start by spreading them out to only one pill four times a day for three days, then three times a day, then go down to twice a day, then only at night for a couple of days. You must be committed to this and must be willing to withstand a certain amount of discomfort.
You will most likely be irritable, moody and restless for a few weeks, but codeine is not a strong opiate and is relatively short active so you should feel better soon. Good luck to you and let this be a lesson to all: just because a medication is over-the-counter and readily available does not mean it is not addictive.