When i had sex for the first time i bled, spotted for 4 days. would that happen again if i had sex again?

Not likely: It is possible, but it is more likely that you would not have that problem again - at least not as much bleeding. Penetration is, in a way, trauma to your pelvic area - if it has not been exposed to that much friction or exposure before. Be sure that having sex is the right decision for you, and always use protection and contraception if no desire to be pregnant. Best wishes.