Hello havingproblems123,
I'm sorry you are experiencing this painful problem.
Did you start having sex for the first time three weeks ago? Or were you having sex before that, but it only started to become painful 3 weeks ago?
Is there a doctor you can talk to about the pain you are experiencing? There are a few different reasons why you may be in pain. A doctor can help you work out the problem and find a solution.
Remember that you don't have to have sex if you don't want to. Please look after yourself and respect your body. I think you should tell your partner that sex is hurting you, and that you need to stop until you can work out what's wrong. If your partner is considerate and respects you, it should not cause any big problems in your relationship. He will probably be concerned that you are in pain, and would want for you to enjoy sex. If he does not care about you, I don't think you should be having sex or be in a relationship with him.
If you still want to be sexually active, you could try oral sex or other activities that don't include vaginal penetration.
Please see a doctor - you should not have to put-up with this pain.
No diagnosis, lots of opinions, and a bunch of issues that I haven't quite figured out.