alright, a few things.
yes, it simply looks like a nitrogen deficiency, nothing too bad, i'd guess the feeding you gave it should do the trick.
also, in your situation, dont be afraid to really soak the soil. overwatering isnt watering too much at once, its watering too often. giving it small amounts of water many times a day isnt the way to go.
It's ok to really soak the soil when watering, i'd recommend doing the weight method
basically the next time it needs water, really douse it. get as much of the soil wet as possible, almost like a flush. then lift the pot and feel it's weight. DO NOT water again until the pot is much MUCH lighter, till the top soil is definitely dry, and the plant is actually JUST beginning to wilt. then water it thoroughly again. These waterings should be as slow and thorough as possible, mix up the soil around the rim a bit, pour it on nice and slow, when the soil starts getting to its maximum water carrying capacity and you put more water in, it will basically run out the bottom...and you'll hear a sucking sound as fresh air is drawn in the soil surface, this fresh air is really important, slight waterings dont really do this for you.
out there in the sun and high temps, and probably low humidity, you'll have aggressive transpiration, you might need to do this watering more than normal...but you definitely want the plant to have water available.
also, miracle grow all purpose is...used by some people, but generally not considered great for herb, so i'd consider looking into something more geared towards herb. (and a higher N ratio for the vegetative cycle)