I used shampoo as soap now have a red bump on my penis and it hurts when touched and is sensitive. did i get allergic reaction?

It's unlikely: Typically, an allergic reaction involves a larger area than just one bump. The bump could be a folliculiltis (inflammation of the hair follicle), a viral process (like a wart or molluscum) or some other process like an angioma (blood vessel growth). If it doesn't go away, you may need a medical evaluation or biopsy- see a urologist or dermatologist.