Every body is different and unfortunately these effects should only last up to 3 months max, if your still experiencing problems, you may have to go back onto a small dose of duloxetine again. I always recommend being on duloxetine for 12 solid months at finding the correct dose for you
Unfortunately smoking does affects the amount of duloxetine in your system and blood stream meaning that you will loose between 40 - 50% of the duloxetine dose you take. It is not uncommon for people to have their duloxetine prescription increased if they smoke. Unfortunately it is not uncommon if you miss a dose to be experiencing these problems if your on a high dose, my patients even at a dose of 30mg do experience brain zaps, nausea and vomiting even with just one day missed. This is why duloxetine should be withdrawn extremely slowly and only under professional help