These rust spots came out of no where help

Went out for the day and these rust spots appeared I am 4 weeks into flowering

Jb,
You must know that you should provide more info.
What I want to know is what Mg are you giving your plant. Now might be a good time for some epsom salts...
JD

I gave it a good shot of Epson salts last night will take a look at her when the lights come back on

could be p deficient