My Egglants are Turning Yellow

I was ecstatic to know that I could be growing another variety of eggplant coz mine was starting to turn yellow. 

Although, I did have some hunches of why it was doing so. I planted 4 eggplants in one pot and I added a different kind of soil a month ago. Maybe that was contributing to this phenomenon. So I did further research and these are the things I found out:

My Recent Vegetable Harvest

I've been busy with work that I seldom visit my mini vegetable garden anymore except in the morning when I water my plants so it was such a lovely surprise when I saw how many fruits they've been producing. I've actually been cooking my eggplant harvest almost everyday now and will probably be eating more of those the rest of the week, considering that I am running out of groceries.