This could be balanitis, a fungal infection, or a variety of other conditions.
It shouldn't be embarrassing. Loads of men get infections like this all the time, and the longer you let it go untreated, the worse it will be.
Balanitis may need antibiotics, so don't try to treat it yourself - just go get it checked. To your doctor, your penis is just a body part, like your elbow or knee. There's no need for shame.
Hmmm. I don't know how to tell you. What's more embarrassing: showing your **** to a professional, whose sole purpose is to treat your illnesses, or having serious health complications over some stupid infection/std?