but nothing showed up until I downloaded a flash player upgrade ... and woosh everything went to ****.
And that was the mistake. I would have to presume some web site insisted Flash needed to be updated with a popup, and you then downloaded and installed a file from that site.
Never, never, ever download anything a web site tells you to install. Unless it's directly from Adobe, a file a site claims is a Flash player update will always be fake. And will always contain adware, or worse.
The only place to download the Flash Player is directly from Adobe. Ignore any other site prompting you to download Flash, Shockwave, a codec, or anything else they claim you need to view or use the site.
Just from the little I can see, you have a LOT of garbage on your Mac. Avast actually being one of the worst things you have installed. Get rid of it and never install any AV software again. They are all useless and are virtually all known to make your Mac run worse instead of better.
You have at least four different types of adware installed, and from the sounds of things regarding Chrome (only happens there), you have at least one Chrome plugin causing a lot of ads to be displayed, and possibly also that fake warning insisting you call a number for help. DO NOT CALL THEM! They are crooks. There's nothing to fix because there's nothing wrong. Chrome is simply caught in a JavaScript loop. You dismiss the popup, and the JavaScript action displays it again.
Do this the easy way. Download and run MalwareBytes for Mac. It will locate and offer to remove any adware, rogue browser plugins and other junk it finds. Since this junk is changing daily, it may not find everything, but it will at least be a start at removing a lot of it. And to repeat, get rid of Avast.