My 13 Month Old Has Developed A Rash At The

My 13 month old has developed a rash at the nape of his neck. I have noticed him scratching the last couple of days so it must be itchy. It is not overly red, nor is it raised. It's very hot and humid where we live currently and he has been sweating a little bit around his neckline. He seems to be clingy and grizzly the past couple of days also.

He had a fever almost 2 weeks ago along with conjunctivitis but nothing since, and is currently on antibiotics to clear up sinus and phlegmy chest which is from a virus turned bacterial. However no fever or any other symptoms for the past 8-10days.

Its just a small light res rash at the nape of his neck. Could it be heat rash?