Welcome to HCM.
You had not mentioned your age, whether married or not, circumcised or not, whether you have diabetes
or not. These information will provide more information about your condition.
Redness and sensitiveness of penis indicates that you are having balanitis
(Inflammation of head of penis - Glans penis
). This may be due to irritation (Soap, external applications, smegma etc.) allergy
, yeast infection and other rare condition. Blood tests for STI will be usually negative only.
An experienced Dermato-venereologist can identify the cause with a detailed history, investigations and easily cure the condition.
Wish you a speedy recovery.