Hi there...I can understand your concern. It looks like you could be suffering from balanoposthitis, secondary to candidiasis, irritant application, etc. It is very common among diabetics. So your sugar levels should be checked. Also other stds like gonorrhea, herpes will have to ruled if there history of exposure. You will require detailed clinical examination. So kindly consult a dermatologist for further evaluation. Till then use only lukewarm water to wash your genitals. Avoid any soaps or antiseptics like dettol.