normal discoloration on lower leaves?

So what I see is too much nitrogen in flowering. The very lower leaves will turn yellow and start falling off slowly is what I found to be best in flowering. So it is getting some but still using some from plant. Why because nitrogen can hinder bud development. The tips burned is the plant wanting more potassium. As long as they are burned straight. If burned up and going in like a curl it is nutrition burn. Your flowering nutrition ratio for npk is 1-2-3. That was really all I seen. Loosing lower leaves is ok. I cut the bottom side out a lot of times to remove airy bud sites. Good luck and hopefully I helped. Happy growing.