My Pre has been getting more and more annoying over the last few weeks.

First I noticed that sometimes when I slide open the screen it doesn't come on.

I have to close and re-open it a few times and finally in comes on.

Other times it comes on, but touching it has a delay of 5-6 seconds before it does anything.

Other times it doesn't respond at all.

Again, opening it again seems to fix it.

This week it has decided to cut off on me when I open or close it (randomly) and occasionally while I'm just texting.

I did a bit of searching but I keep ending up on threads talking about needing to shim the battery to stop it from rebooting. I did have to use that trick with the stock batter but I've been using the 2800mha Seidio since august.
It has no wiggle to it that I can tell so I don't think that's it.

When I turn it back on it shows me the battery symbol with the question mark.

Any ideas?