Hi MLady,
Since your using the epuffer magnum, which uses a disposable cartomizer, you can try doing the "refill" method with DIY or other vendor bought juices as the method described here won't work for you. Search out on the forum with keywords "refill" "refilling" "magnum" "smoke51" and it should give instructions on how to do it. If you have difficulty finding the related posts, pipe in and I'll try and search it out for you.
The cartomizer design, albeit convenient, is pretty hit and miss with satisfaction. Sometimes they don't fill them enough, sometimes they change the recipe, but most of all its very difficult to monitor the "wetness" of the cart, and with the disposables, the atomizer is a filament that runs through it where if it gets too dry, it will burn its insulator or wadding in the cart and that is simply NASTY tasting and can very much irritate your throat !!
I see you started using this device back in November last year..... Is this an issue that has just started up with you ?? Did it start after a "new" batch of cartomizers, strength, or flavour ?? Is it something that simply is coinciding with perhaps outdoor allergies ?? Lots of possibilities here, but I don't believe that if you have been using yours since last November without issue that you suddenly began an allergy or low tollerance for PG which is what is used in the magnum cartomizers.
I started off with the same style of device, but a smoke51 branded product. Although I enjoyed the convenience I've moved on to a 510 manual battery and DIY (as well as vendor purchased) juices and find it much more satisfying regardless of the extra time in prepping the carts. I now use my 51 as a spare should I run low on supplies or my battery unexpectedly gives out on the 510.
Let us know a bit of history with your use, as stated above, and perhaps some other chance recent changes so we may try and advise you in the right direction.
VapeOn,
Greg