I have a son who is 4 years old. his penis constantly swells up because of dirt under the foreskin i clean it everyday morning and night but it's become so sensitive that he doesn't even want me to touch it i want to take him for circumcision?

Start with his doc: Have your son evaluated by his pediatrician first. A possible infection will have to be ruled out first. In case a circumcision is needed, his pediatrician will be able to further coordinate.

Penile infection: Since your son is having recurrent infections in spite of what sounds like good hygiene, a circumcision is appropriate treatment. Take him to a urologist for evaluation and treatment.