What could be the cause of my son's foreskin being swollen and red? he is 2 years old. how can i help treat the swelling and redness?

Infection: It sounds like your son may have phimosis with balanitis a common inflammation/infection of the foreskin. In any case it should be checked by the doctor to see if a serious infection or not. It can be treated fairly simply with creams and antibiotics usually.

Needs examined: Allergy, irritation such as detergent burn or infection are possible causes. Needs to be examined. These are in circumcized boys. If not circ'd, then phimosis , where the foreskin is pressing the shaft too tight. This needs seen asap.