#slow

I'm having problems with my lower leaves yellowing at the tips then some brown spots. Does this look like a type of deficiency or a pH problem in my soil? I have no idea I'm a noob so I'm learning as I go. I'm hoping someone with more experience could give some input about this. The plant is...

This little girl opened up her cotyledon leaves 5 days ago and for a couple of days she grew slowly and now it seems like she either stopped growing completely or is growing really slow. Does anyone know what her problem might be? Pictures below: This is her 2 and a half days ago.. And this is...