Sometimes I masturbate before I go to sleep at night. Usually nothing is wrong, but sometimes (and this always occurs at night, I've found) after I masturbate, a few minutes later I have to urinate. And when I do, it is usually very painful. The feeling doesn't pass either. My scrotum usually gets very tightened up, and there is painful feeling above my crotch. Usually I just sit there, drink some water until the feeling goes away. ANY idea what this is?

1) I've always used condoms combined with a sponge for birth control. That worked well because if anything happened with the condom, there was always a backup — it made me feel safer. Then I get to New York, I go into three drug stores, and none of them have sponges. Now what? I don't want to rely on just condoms, I don't want to take pills because the whole hormone thing is rather frightening, and a doctor said that diaphragms make you more prone to get urinary tract infections, which I get frequently. So what am I supposed to do? What's up with this total absence of sponges?

2) In exploring other forms of contraception, what is the reliability rate of the "sponge"?

I am not sure who the father of my son is. Is it possible to tell the father of the baby simply by knowing blood types and Rh factors of myself and the potential fathers?

I was wondering about the depth of the vagina. I've read statistics that say that the average vagina is only 3 to 4 inches deep. This seems way too small to me, since the average penis is considerably longer than that. Wouldn't that mean that most penises would crash into the cervix repeatedly during intercourse? Since this obviously doesn't happen, my question is this: does the vagina actually elongate during intercourse to accommodate the entire length of the average penis?

Me and a guy were having a discussion in reference to puberty. A question came up in the discussion: are males born with their sperm? We went to the Sex Education Dept. of our school, and they weren't able to give us an answer, and recommended your site. So the question is, are males born with sperm, like females are born with all of their eggs?