Although, if this is week 7 from seed (I'm not real clear as to what you mean, "week 7..."), then you definitely need to up her nitro intake. Too, I do see a bit of purpling in the stem, which may be a symptom of a mag deficiency. However, some strains do carry the purpling, yet I would still add 1 teaspoon of Epsom Salt to one gallon of Ph'd water to get her healthy again.

*Note:* By giving her Epsom Salts, the purpling of the stems will not completely go away; however; new growth will be greatly improved and her leaf tips will stop pointing down and begin to straighten back out.