Having problems with android phone?!

Hello. I have been dealing with multiple problems with my android phone:
1) when I try to download and install apps such as Facebook and twitter, it keeps telling me that they can't be installed.
2) I uninstalled the updates for the Google play store and not only do the apps fail to install, but I can't reupdate the Google play store app.
3) when I try to download and install the Google play store app from chrome (I know doing that is considered a third party app and I changed the settings to allow third party apps) it keeps saying "app not installed" (that and another third party app).
4. I keep getting notifications saying "unfortunately (app name) has stopped responding". (Apps such app poops google+, twitter. Etc.)

Also, I have rooted the system memory and all of my apps are on my SD card (32gb). I know it's not a virus because I have a really good antivirus software on my phone and it said that there's no viruses.

My phone is a Samsung Galaxy Grand Prime with android 5.0 lollipop.

If you can help me with these problems, it will be gratefully appreciated!

Thanks!
-Tom

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