Suggest Treatment Erectile Dysfunction

sir my top of penis i.e glans area changes colour from pink to brownish black.Almost 1/4th part of glans area have changed the colour. I have used a ayurvedic medicne for sexual enhancement for 2 months last year.My doctor friend told me that the problem may be due to that suppliment nd also told me thai it may contain steriod due to which the veins present on the head of my GLans area may get demaged .NOw a days i am facing some issues with my erection. kindly guide me to get rid of this problem.I am 40 years old