Battery not indicating drain or charge

I'm running into an issue that just started this week. I was having lots of battery issues a few months ago, so I replaced the battery with the one purchased from here at iFixit around 4-5 months ago. All has been great since then until this week.

I noticed that the battery percentage seems to be "stuck" on a certain value until I reboot the phone. I plugged it in last night with 23% left, and this morning it still said 23% despite the charge symbol showing. I rebooted the phone and it suddenly showed the correct 100%. Looking in Usage it still showed the standby and usage numbers from yesterday, but when I plugged the phone in again, it all reset to 0, indicating that it had a full charge.

Within an hour, I was browsing FB and Instagram, and the phone shut off and rebooted itself twice. When this happened, the screen suddenly had a weird look on it for a split second, before turning off, and then the Apple logo coming up. Did that twice in a matter of minutes.

So now it's mid-morning, and I have used the phone some, but it still shows 100% battery which I know is not right. Looking in Usage, now for Usage and Standby since last full charge, it just shows dash marks, where this morning it said "0 minutes" after had rebooted and plugged in the phone again.

And just now I rebooted the phone again, and it's now showing 86%, which seems correct based on the usage I've put on the phone this morning. Usage time since last full charge still shows as dashes.

Again I'm using the battery that comes in the kit available here on iFixit, and I haven't had any problems at all until just this week. I do have the problem with my sleep/wake button that Apple has documented and I can get fixed, just haven't gotten around to taking it to the Apple store yet.