Im 33 year old, fit male. I'm having trouble maintaining my erection beyond a minute or two since past one year or so. Withbl constant stimulation it lasts for 5-10 min sometimes. Previously I would have strong erections that would last as long as hour sometimes with basic stimulation. I'm not aware if this is psychological or physiological. I do not have trouble getting an erection- merely maintaining it. What could be the factors leading to this and should I see a sexologist (psy) or MD (int)