Ethos Apex Bag Seed

This week I started seeing some brown spots and the new growth seems a little different than before so I added some Cal-Mag Pro to see if that helps any. Overall I've only given notes twice at very small amounts because the plant looks to be growing fine. I figure for my first grow I'm better off using too little nutes as opposed to using too much. I made a rookie mistake and am using Miracle - Grow Performance Organics Potting Soil. I'm hoping I've used up most of the nutrients that were in the soil so I have a little better control during flowering. I flipped the lights to 12-12 two days ago.