Hello,
Smooth red itchy bumps on the head of the penis is commonly caused due to sweat, bacteria, dead skin that leads to itching, rashes, redness or discharge under the foreskin. Sweating and friction from tight clothing can also cause such symptoms. 
Contact allergy, latex condoms, spermicides can trigger itchiness. Take care of your hygiene, Avoid harsh cleaning products and wear loose cotton clothing to relieve symptoms.
You can apply a thin layer of ointment 
hydrocortisone or ointment 
clotrimazole on the area affected. Ointment 
Soframycin / Neosporin are equally effective. However, such rashes may also be indicative of 
genital herpes, to stay on the safer side get clinically examined and get STD tests done. If positive, you will be treated with antibiotics and antivirals.
Take care. Hope I have answered your question. Let me know if I can assist you further.
Regards,
Dr. Nupur K., General & Family Physician