I Have Some Round Ulcer Like Structure At The Inside

i have some round ulcer like structure at the inside of the penis skin...
and from couple of day having pain while passing urine or burning sensation...
it gets reduce but after sex or masturbate when i go to pee it pains again...
doctor has given me alkasol and becozym c forte...
could you tell me why such problem i am facing and wat is the use of these medications