Allergy?

We found out my son has seasonal allergies, nasal issues mostly. I've noticed when he goes out in the grass he develops red dots so I'm guessing it's from whatever grass we have. No one else in the family, including his twin sister, gets them. We live in southern VA, not sure what grass it is but it pops up fast. Can anyone say if his dots look like it's from the grass? Also, is there anything I can put on them? We had this issue last year and hydrocortisone helped but can't use it everytime we go outside.

It's on his elbow in this picture, he literally rolls around in the grass 🙄