Hello, Welcome to Healthcaremagic.
There are plenty of causes for red spots in penis head.
Even mild trauma can cause red spot on your penis.
One important sexually transmitted diseases is known to cause Red spot in penis is
Syphilis.
So it is better to do VDRL test to rule out syphilis.
If it is found positive, Penicillin will be used for treatment.
Not only syphilis cause red spot.
Other causes are
Herpes infection, Candidal infection,
Impetigo are the other causes. these need
antiviral, antifungal and antibacterial respectively.
You need physical examination by either a physician or
dermatologist to confirm diagnosis and further management.
If any doubt, kindly reply.
Hope this helps.
Take care.