Pluto Auto HELP????

HELP??? [UPDATE: I’m starting to lean towards a lack in nitrogen... when I added the nutrients that was its first top dressing and didn’t have on schedule to do another feed for a couple weeks and hoping to do the last feed by week 10 to start natural flush. I was wanting to stick with dry amendments. Including the Pluto my other 3 are starting to show signs of more yellowing and brown this morning on new leafs. Should I try to add just a little nitrogen blood meal or 4-4-4 even thinking about brewing a tea in the near future?? Just don’t want to add to much?] Hi! I’m currently on day 44 of my first indoor grow and would appreciate any help generated towards this way. My Pluto from Ethos Genetics was thriving all the way up intill about day 35. Using Happy Frog Organic Soil with soil ph between 6-6.5 indoor tent temp at a steady 70-77 degrees humidity 40%-50% added a lil nutrients around day 37 the last week or so I noticed some yellowing starting on the bottom older fan leaves before adding the nutrients. water ph 6.5 usually watering them about every 2 days. On Friday June 25th I noticed the yellowing starting from the bottom climbing up with brown spots starting to be visible on the top of the plant and leaves dying off at a good pace and definitely seeing a little bit of stunned growth on the baby leaves. I’m thinking maybe nutrient burn with a mix of under watering and perhaps even nutrient deficiency?? I have 5 autos in my 4x4x6 spider farmer tent and my other 3 are starting to yellow at the bottom up as well but a little slower even after adding some nutrients only 2 days after the Pluto. It’s killing me more everyday seeing them in this state and just wanna figure it out with perhaps a few others opinions before making any moves. Thank you ahead of time!