here's another

overall tree

another pic

this is from a different tree, no spots, but these leaves have yellow veins in the leaves. None of the other trees have this. Any idea what the veins mean?

Shumard (q. shumardii) and Texas red oak (q. buckleyi) are both also in the red oak group, so question is what species of red oak you have. Photos of back side of leaf, terminal bud, bark, and acorns (once you get some) can help in telling the reds apart, because it's often not obvious... and even more confusing when they hybridize. May find more who are good at this over on the GW Trees forum.

Your tree looks really nice at three years regardless of its pedigree. The big box stores have gotten better at stocking trees that do well locally, so less likely to be selling a Nuttall's (now q. texana) or some northern red in alkaline FW.

Might look into Tubakia Leaf Spot fungus to see if it matches your tree's symptoms.

The tufted vein axils on the backside of the leaves was the first characteristic that confirmed our squirrel planted oak as a Shumard. This is described here:
The leaf undersides show a distinctive feature of Shumard Oak: tan tufts of hairs in the axils of the veins. Related oaks may have tufts of hairs in the veins, but they tend not to be as pale tan or as tufted.

Didn't mention it before, because was not sure whether q. buckleyi has the same characteristic. Did find the linked Google books preview that says they are present, but, unlike q. Shumardii, inconspicuous. This {{gwi:486386}} is probably the easiest way to confirm a Shumard or its hybrid.

Here is a link that might be useful: Trees of Eastern North America preview