Blog Back-End and Images Loading Extremely Slow?

For the past week my blogs have been acting a little bit slow/buggy, and it’s gotten really bad over the course of the last 24-36 hours. I feel like I’m constantly seeing “Waiting for…” messages at the bottom left of the screen that were never an issue until a few days ago. Sometimes they say “www.<myblog>.com” and sometimes they’re “pixel.wp.com” that they’re hung up on.

My sites are now operating so slow sometimes that it seems like it’s the stone ages, while other times they still seem to load okay–but mostly they’re running badly. This is happening both on the front-end and the back-end, and it seems to be that when the sites do connect and load, it’s the images that take forever to load. They’re not huge or high-memory images either.

I updated to the latest version of WordPress, updated all of my plugins, turned all my plugins off (including Jetpack) and reactivated them one at a time, changed my theme to 2016–no luck. Everything still loads sporadically slowly.

I checked with my hosting provider (BlueHost) and they told me that there’s nothing wrong with the server my sites are hosted on and no problems at all on their end.

I tried turning on Photon on one site, but even with Photon on some of my images are still loading slowly or sometimes not at all. I tested SuperCache on one domain and W3 Total Cache on another, but neither made any difference.

I haven’t made ANY big changes (or even little ones) during the past week, so I just can’t do know what’s going on. I was thinking about trying out CloudFlare or something, but that seems like it might be a stupid thing to do when I don’t even know what the problem is and why the sites’ speed/reliability suddenly went to crap.

I’m really not sure where to go with this. Does anyone have any input on what else I should try (other than just pretending there’s not a problem and hoping it goes away)?