Thanks for your query,based on the facts that you have posted it appears that you have itching on under surface of glans penis
and your foreskin is red and thick .
Many a times itching of the genitals is a presenting symptom of Diabetes
Please get your blood sugar tests on empty stomach and 2 hours after lunch done to rule out diabetes .
If you turn out to be diabetic you will need to take opal hypoglycemic drugs as per advise of a qualified Physician,
In the mean while take anti fungal medication
like Fluconozole and topical anti fungal jelly for local application .