Hello, I'm new to this site becuase I need help w/my baby!!! Can you help please!!!

Her leaves started to yellow on bottom like 2 days ago. Can you tell me what's wrong??? Please help!!!
The first pic is w/a flash, the second w/o, the third is a close-up..Please help my baby!!! And thanks in advance!!

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That is due to a lack of nitrogen reaching the plant. Your ph is probably swinging too high, most municipal water is very alkali. I may be wrong on the cause, but for sure is a nitrogen issue. Kinda young, err small at least, to have that problem. Kinda looks like its a runt pheno, too. Stem is awfully thin.

Ph of water is off, or it needs nitrogen.

Have you been feeding it? If so I would suggest nute lock, if you have not been feeding the above posters have made the best suggestion IMO.

Any nutes in your medium? That's an awful big pot for that small of a plant. Careful with overwatering.