What should I do?

Nothing, just continue as scheduled. Plant is too close to being finished that anything you do now will not "fix" what has already happened.

All you can do is correct course and feed it properly... plant can only heal so much per day and any necrotic spots won't heal at all. The plant does all the work.. we either avoid mistakes or make them. we don't control much beyond keeping them happy. It's still alive. It'll still give you a harvest.

You can use pH buffer liquid i.e. from aptus. It will stabilise your ph

Give them some nutrients to stay healthy and keep ripening them.