Thanks for your query.Based on the facts that you have posted it appears that you have a sebaceous cyst
over shaft of your penis.
However final diagnosis can be confirmed only on clinical examination by a qualified General Surgeon
The penile skin is rich in sebaceous glands and hence prone to get more sebaceous cyst due to accumulation of sebum beneath the skin.
Normally they fade away without treatment however they need to be treated if increase in size or get infected.
Please consult qualified General Surgeon for clinical evaluation and further treatment.