I actually went so far as to factory reset my phone. I'm in a situation where I'm not allowed to run a custom ROM (company phone) and my phone was overheating and draining in a couple of hours (as posted before by someone else). I've also been running the stock 6.5 since it came out and haven't experienced the SOD until the 19th or 20th of May.

Gmail does seem to have been the culprit. Oh well. I was still having the issue today, oddly enough. I actually performed the factory reset today at lunch, about 12:30 EDT.