My cap in the front of my mouth has a post that goes into my gum. It is extremely loose. How can I get it out?

I would contact your dentist's office and see if there is another dentist covering while your dentist is away.  If no one is covering the office ask if there is another local dentist that they work with that can help.  If you leave the post/crown in its current state it is easier for food and debris to get stuck underneath which can cause a bad odor and you are risking fracture of the tooth root.  You need to have this checked asap!Also, you may want to discuss why this crown/post is coming out so often.  It may be that there is insufficient tooth being held onto for the restoration to have good long term retention and support.  

I would suggest getting an appointment with an endodontist. They should be able to remove the post and recement it. The bigger question is why does it keep coming out? I would ask the endodontist to do a complete exam to make sure the tooth isn't fractured.

I think you should see a dentist.  If you cannot wait for your dentist, maybe he has someone covering for him