I took my eldest daughter 14 (15 in November) to the doctors because of her spots. Some of the medication you can buy over the counter "burns" the skin and causes scars.
When I was her age, I was given "acnegel" (different name now) although I didn't have acne as you would describe it.
The doctors diagnosed my DD with acne (she was horrified), although, again, it is not acne, as anyone would describe it, but she been given medication and it has helped immensely (same as "acnegel", but different name).
No spots on forehead, no spots on chest or back.
Not called "acnegel" now but same medication. Well worth your son going through the embarrassement of going to the doctors (with his mum) and being cleared of all spots (like my DD is now) within 3 months.
My dd (nearly 15) swears by it. She hates Clearsil and other medicated washcreams/spot cream, etc. you can buy over the counter.
The medication my daugther has been prescribed by the doctor is the mildest form, if it didn't clear up there is a "stronger" medication, but the weaker solution has worked wonderful.
So wonderful in fact that she wore a bikini on holiday this year (and she is very embarrassed of her body - although I told her to be proud - she is slimmer, about a size 10, bigger boogs - 34 DD, very pretty). Make the most of it, but worse for her, at that time, was the spots - NOW ALL CLEAR.