I did a bit of a hack in the circuit. I need to use voltage dividers to measure the voltages on the individual cells, but instead of building 7 separate voltage dividers for all 7 cells, I split the divider, and added a multiplexer in the middle to switch between the different cells. In addition to making for a fairly simple circuit, it would've also allowed me to "switch off" the voltage dividers completely, so there wouldn't be any drain on the batteries. It seemed like a good idea, but the results were questionable.
What's the short term fix? Having 7 "full blown" voltage dividers. I wanted to try it on this PCB, so I did some funny air circuit fun.
Longterm, I could use a different method of measuring, but that's for the future