Alot of people do experience this in their first few days of vaping. I know you vaped before, but after months of smoking again (especially NewPorts) the "gunk" has built back up in your lungs. You will likely cough alot the frist couple of days, but it will go away. The throat burn is concerning though. Juice can go bad, but typically has a shelf life of 2 years... I would say go for a differant juice. If you are a menthol person, and dont mind the Chinese juices (dekang) try the Strong Mint from
LitecigUSA or since you mentioned V4L, their Peppermint WOW juice is awesome too. So here is a broken down list of what I would suggest:
1) Grab some new juice and/or cartos (possibly VG based in case you have developed a PG allergy)
2) Try to push through the cough for a couple days to see if it lightens up or goes away
3) For the first week at least keep water with you at all times
4) A cup of chamomile tea with little bit of honey 2 - 3 times a day to help with soar throat if you get one
i vaped for almost 8 months successfully. but a lot of stress along with a pocket full of batteries in the washer/Dryer catastrophe, i started smoking again. now months later i am really trying to vape again and every time i try i cough my ... off and my throat burns! can juice go bad after a few months? it looks no different. also the carts i have do the same thing. i use V4L carts (empties and pre filled). i dont get it. when i started the vapor was always smooth and easy to inhale, like a cig. i smoke Newports so it cant be that the nic is too high. anyone have similar experiences? 
