I just installed new bahia sod in my backyard.

Sorry about that.

Yeah my condolences.

The fact is bahia will grow where other grasses won't.
A photograph would likely be worth a thousand words in this case.
What you may not have known is that bahia can be easily burned by fertilizer. It really shouldn't need fertilizer in Florida this time of year.

A soil test could also shed some light on the subject.

Stop watering, fertilizing and caring for it so much.

Bahia grass forms an extensive root system, which makes it one of Florida's most drought-tolerant grasses. It performs well in infertile, sandy soils and does not require high inputs of fertilizers

Heres a few tips for you:

Fertilizing:
Fertilizer should be applied to Bahia grass in two to four applications from spring green-up through fall. Never use a weed-n-feed on Bahia. Apply a complete fertilizer at the rate of 1/2 to 1 pound (slow-release) nitrogen per 1000 square feet.

Watering:
Irrigation is needed when leaf blades begin to fold up, wilt, or turn blue-gray in color, or when footprints remain visible after walking on the grass. Apply 3/4 to 1 inch of water per application. You should be able to go (at minimum) a week or two between waterings. It is very important not to overwater Bahia grass lawns as this weakens the turf and encourages weeds. Bahia may go dormant, turn brown and stop growing. It will revive and resume growth upon regular application of water.

Mowing:
During times of active growth, bahiagrass should be mulch mowed with a sharp, balanced blade every 7 to 14 days at 3 to 4 inches of height. Higher mowing heights promote a deeper, more extensive root system that enables the grass to better withstand drought stress. Remove no more than 1/3 of the height of the leaf blades with any mowing.

Follow the above and you'll be just fine.

I put Milorganite on it several times to green it up - also fertilized it recently.
What does this mean? Milorganite is fertilizer.
Also, how much is several times?