2006 Prius having sudden issues

Hey guys! I’m new to Prius chat and I’ve only owned my Prius for about a year now so forgive me if what I say comes off as confusing. I bought the Prius from a seller on Craigslist. My 2006 Prius had right at 180k miles when I bought it last February and it is now at 222,687. It’s never been in a wreck and it’s had synthetic oil changes every 10k miles. The reason I got on here was because my Prius has recently in the last 2 weeks started doing some really weird things. The first thing I noticed before having any other problems was my hybrid battery draining quickly and my average MPG dropped suddenly.The morning I got up and went to work I noticed my hybrid battery wasn’t staying charged as much and my average MPG had dropped all the way to the upper 30’s. Usually I would average 46 and above and that’s with me being heavy footed. The hybrid battery would also always stay in the 3/4 range and it was wanting to stay around half and then sometimes dropping all the way down the one purple bar. I tried to ignore what I had noticed and thought maybe it had to do with the weather or something else and it would correct itself. About a week later, I had went to a friend’s house about 2 hours from where I live. When I started my Prius and had gotten not even a whole mile, the red triangle light and some other warning lights came on the dash and the hybrid battery had completely lost all of it’s charge and the ICE wouldn’t cut on. I had to pull off on the side of the road as quickly as I could and put the car in park and turn it off. My first thought was to unplug the 12v battery and see if that would reset anything and to my luck, it seemed to somewhat fix the issue. All of the warning lights were still on but the ICE kicked back in and started charging the hybrid battery so I was able to start getting down the road. I cut it off again to fill up with gas on the way home and when I turned it back on the lights were still on but everything seemed to be running fine. The next morning the red triangle appeared for just a second when I started my car and then disappeared. The check engine light was on but later in the day it eventually went off. Some other weird symptoms my Prius has had is the dashboard lights sometimes not coming on and also the A/C fan will sometimes not come on until I get going down the road a little ways. Another problem that just started today was when I would brake at a stop sign or make a sharp turn, the “red triangle of death” would come on for a split second and beep. I’m not sure if those are separate problems or if they’re somehow all related to the same issue. I’d really appreciate any advice I could get from you guys. I don’t have a ton of money to spend on trying to figure out the problem so I’d really appreciate it if someone could steer my in the right direction of where to start at.