Hi, Welcome to Health care magic forum.
As you describe, it may not be the
syphilis,all the above features may be secondary to the
diabetes, probably when he is taking more of the sugar,and sweats,there is possibility of getting cuts,and
fungal infection on the penis, and weakness as well.
I advise you to
consult a dermatologist for diagnosis and treatment.
I usually prescribe to my patient with such symptoms correct the blood sugar, and ask to have a follow up regularly.
Phexin, grisofulvin, and multivitamins.
Wishing for a quick and complete recovery. Thank you.