You're probably at a high ash accumulation. If you don't get it to a shop you will start getting derates, eventually it will shut down to idle speed. Need to get a laptop and technician on it at this point.
Make/model and year of truck and engine? Ditto Mike's question and when was the last time the filters were pulled and cleaned? Take it to a shop with a computer and have them run a forced regen, record the beginning and ending pressures and the temperatures. Check all of your wiring connections. Examine your exhaust system from the manifold where it bolts to the engine and all the way back to your stack. Pull the sensor on the engine and swab the soot out of it.
There is something wrong with the emissions system, so it needs shop time. 350k miles is about the point where you need to have the DPF filter serviced in any case. A 2014? It should still be under warranty.
if you had it in the shop two months ago there is some problem. could be coolant getting into exhaust ( it takes very little ) could be bad quality DEF have you had the problem after buying it at a certain place or, do you idle more than an hour a day. I have had all these problems. i believe the first removal and burn was at 550K second at 6 new catalyst/filter at 750.mine is a2011 witha rebuild in the middle,just over 6, had a water jacket fail (cylinder liner). it is troubling to me that a 2014 is quitting so soon but i'm not a big mileage maker could be you are matching my mileage already. i assume the shop found no outstanding faults when you had a problem 2 mo ago. if this is true i would go with the bad quality DEF besides it is the easiest fix. i saw some snake oil for sale that was upposed to remedy def problems i think it was a lucas product. i wonder- you need a better authority than me- if putting some kero in youir fuel would help. could also lead to a fire, but in the good old days this was a panacea in the winter.when i had your problem everyone (shop techs) said i had to let it run till it went out. so i parked it out in the middle of the yard and let it run, all day, 10 hrs, that was just before second removal and furnace burn, and the light never went out.