FLUSH!!!
It looks like you have a combination of sunburn (pic 2) and nute burn.
Luckily you're on the home stretch and have some good bud development.

Someone may correct me, but if my plants looked like that I'd check that the light is not too close to the growing tip, Flush, and continue ferts with a weak bloom formula.

The yellow lower fan leaves aren't a big deal at that time in flowering. They shouldn't be QUITE so yellow quite yet but that doesn't mean that you need to give the plnats a ton of N at this stage.