Dropping in ranking and technical issues?

Hi again! I need some help figuring out an issue I`m having with one of my websites, if anybody out there feels like helping me sleuth. My website started to see a slow decline in organic search traffic starting a little over a month ago (May 6 ish). That traffic is still sliding, and I haven`t been able to figure out what`s going on. Our SEO strategy hasn`t changed recently. Site speed is consistent. Here are a couple things that have been going on that may/may not be related. Any ideas? -All the websites I work on are being converted to a new CMS, and while this particular website (website A) was already converted, a conversion on a different site (B) caused website A to have a few crashes. It was back up and running quickly and before May 6. -Another conversion-related issue: For about a week, an issue on the back end of websites A and B resulted in a bunch of B`s traffic getting attributed to A (major inaccurate traffic spike for A in Analytics). Is it possible that either of those are causing an ongoing slide in organic search traffic? If you were me, where would you look for answers next?