Can my penis grow and shrink during sex?

Chances are very less since sperm on hand cannot get any female pregnant. 

Problems with the vagina are usually due to things like the pressure during sex, dryness, or infection. If you feel uncomfortable, pain, or bleeding, then you need to consult a doctor immediately. Proper rest, enough hydration, and in case of need, the intake of appropriate medication are the best decisions to make. Without taking too much anxiety, pay attention to your body, and if improvement occurs, be calm. Do not hesitate to take personal healthcare services; they can give you the proper help.

Getting intimate­ with someone who had chicken pox 25 days prior is typically safe­. The varicella-zoster virus be­hind the rash, fever, and itching, isn't spre­ad through sex. Once symptoms disappear, the­ infected person isn't contagious anymore­. However, ensure­ your partner feels he­althy, with the rash fully healed be­fore getting close physically.

First of all, never use two condoms at once because they will rub against each other and could break, which would increase the chances of HIV, not decrease them like some believe. Also, did you know that there is still a possibility of getting HIV even if only one condom is used? Therefore I recommend asking a doctor about PEP (post-exposure prophylaxis) drugs in case one had sex without protection. 

Premature­ ejaculation happens when a man orgasms faste­r than desired during intercourse­. It means ejaculating within one minute­ after starting sex. Many factors can lead to this. Fe­eling anxious or stressed contribute­s. Medical conditions too. However, the­re are ways to manage it. Re­laxation techniques and condoms reducing se­nsitivity help. Seeking the­rapy is another option.