The main area of bleached-looking tissue doesn't look like it's due to infection; our plant pathologist agrees it appears to be physiological, which would be damage from environmental conditions. Although some winter drying is well-tolerated by these succulents, where the pads shrivel as water reserves shrink, it may be that it was kept too dry for too long, especially given our drastic temperature fluctuations of the past few weeks. Tissue damage from either scorch or an overnight cold snap (after one of our earlier warm periods) may have taken some time to manifest. While nothing can reverse those symptoms, you may want to keep an eye on its watering frequency from this point forward (which it sounds like you are). If it was exposed to reflected heat and light from the nearby wall(s), that might have exacerbated any vulnerability to scorch.

The corky brown zone in the other photo looks like scab, which is also a physiological condition and may be due to over-watering (ironically) since it is thought to be tied to edema (plant cells are damaged or burst when they hold too much water they can't evaporate fast enough). Which issue arose first (the theorized got-too-dry or got-too-wet) is hard to guess, and it is possible for symptoms to overlap even if they began at different times.

All you can do is to monitor root moisture and maybe try to give the plant more air circulation if you have the option to move the pot further from a wall.

Miri