I am 24 and have problems maintaining erection during sex...i can masturbate and i get morning erections..remedy?

Mental health: An erection is more than 50% about your mind than about your body. If your penis works as you describe then you are either worrying too much and setting yourself up to fail, or you are not attracted to your partners. You may need to get some therapy about this or find a way to get your mind out if the way.

Erectile dysfunction: Let's get some basics out of the way. Morning erections suggests that one has enough testosterone. Ability to maintain an erection during masturbation suggests that blood flow is not an issue, as is more typical of middle age & older ed. Finally, younger age suggests ed more likely a consequence of performance anxiety and/or poor relationship plus tobacco, excess alcohol, work, money, family etc.