I have dermatitis in my penis and area very inflamed .... when i have sex i suffer a lot... what should i do?

See professionals...: For someone of 55 with what you described, one has to make sure if it's long-tight-foreskin-related. For time being, avoid further physical stimulation but keep the area as clean and dry as possible. If not improving in 2 weeks, see a urologist for confirmation and how to help the long-term care such as circumcision as needed. Meanwhile, practice healthy lifestyle and avoid overindulgence. Best.

See derm: You need to see a dermatologist to get your dermatitis evaluated and treated. Until it is clearing up, avoid intercourse. It is important to make sure that the dermatitis is not contagious.

See doctor: Since you did not mention itching, it is likely from an irritation or infection. Either way, you need to see an urologist.