Unexpected super tablet slowdown

Dell Venue 8 Pro Tablet, Windows 8.1

Last night I didn't really shut my tablet down the way I usually do because I just fell asleep with it on ( it goes to sleep itself after a few hours).

This morning I woke up, went to church and spent the rest of the day with my friends. I got home around 9 and brought it out of hibernation, everything was not responding; FF, chrome, the desktop. I waited to see if it would catch itself up but after a few minutes, it didn't so I decided that I would just shut it down and give it a good restart. After a bit, I finally got the shutdown options to open up and selected shut down. It popped up after about 30 seconds but had to do a forced shut down because of all the previous not responding items.

I let it sit for a few minutes before turning it back on and everything was still molasses slow. Plus I got a pop up from the action center asking me to enter my most recent password (I can't understand why I haven't changed it).

It was working perfectly Saturday night, so I can't imagine why all of a sudden it would act like this. I haven't downloaded anything in ages, and am not an active surfer ( seriously, I visit like the same 4 pages, this being one of them lol) so I doubt it's malware but I ran Avira anyway, found nothing, and mbam, which also found nothing. I haven't entered my most recent password yet like prompted because this one account is synced on all my devices so I don't want to mess anything up.

I had to post this from my phone because to type on my tablet is like 20 seconds per letter, it's that slow. Please help me figure out what could possibly be wrong, because this tablet is all I have right now and I kind of need it to work.. Thanks all!