I am becoming increasingly worried that i'm suffering from some sort of erection problem.
My penis is pretty healthy, i mean i keep it washed and i don't neglect it with dangerous physical activities or anything, but over the past few months i'd say it's got weaker in comparison to say a year ago. Me and my partner (Only sexual partner i've had) practice safe sex, and only try anything potentially harmful by taking the right amount of care required - such as anal sex.

While having sex, sometimes it loses the same stiffness as i have when initially aroused. Also with oral sex, or even when my girlfriend uses her hand, it becomes only semi-turgid at times - although when i first start any act of sex, it's very rigid.

Also, after urinating, i use the same muscle that i use to stop mid-flow, to push out the remains of any urine still in my urethra. However - this method now seems to be limited in strength - almost the same way as my penis feels limited in strength during acts of sex.

I know that i may have to elaborate on exactly just what is happening to it, and in what situation, but i want any initial thoughts on what it could be. Just a few different opinions so that i can understand where i should look for more professional answers. Thanks!