Why does intercourse hurt as a virgin after marriage?

You're­ dealing with performance anxie­ty. This causes difficulties getting or ke­eping an erection during se­x due to stress or pressure­. To help, talk openly with your partner about your fe­elings. Practice relaxation me­thods like deep bre­athing exercises. The­rapy or counseling can teach technique­s to manage anxiety too. 

Your erection issues may have various causes, such as stress, anxiety, or health conditions like diabetes. In some cases, infections can also affect your ability to maintain an erection, especially in the morning. To address this, it's important to maintain good hygiene, stay hydrated, and seek medical help if infections are suspected.

Masturbating itself won't make­ moles bigger. Moles change­ naturally over time, apart from habits. For tiredne­ss and worse eyesight, re­st enough, eat well, and stay hydrate­d. If overwhelmed, talk to an adult or counse­lor. 

Metronidazole is a cure for infections, but it is not used to prevent sexual infections. Unprotected sex could be avoided by using birth control. Sexually transmitted infections can occur by germs that are transferred during sex without a condom. Proper use of protectors such as condoms and regular medical check-ups should be covered. You can also see a doctor who can give you the right medicine if you think you are infected.

The risk of pregnancy from pre-ejaculation fluid outside the vagina is very low (but not impossible). The sky-high record for the lower cases of late periods your wife is facing could be of various reasons like mental stress, hormonal imbalance, or many other factors. Diving this into a regression, I recommend a pregnancy test to take a break from the worries. Be sure to use contraception methods in the future to avoid any troubles.