It looks like it could be dollar spot, but unfortunately, it is nearly impossible to diagnose turf diseases in this forum. I recommend contacting MSU Plant Diagnostic lab. Include info such as when and how much you water, when you lasted fertilized, what other chemicals were applied and when. If they need a sod sample they will contact you. https://www.canr.msu.edu/pestid/

Using a hand lens looking at your grass blades, and comparing to the diseases here, you may be able to spot something. http://www.msuturfdiseases.net/browse-by-name/

As you can see, the possibilities are many, and a close examination of grass blades under magnification is usually required.

I hope this helps. Thank you for using our service.

You may also contact the toll free MSU Extension lawn and garden hotline at <personal data hidden> with your gardening questions or visit www.migarden.msu.edu for Smart Gardening resources.