I honestly can't put tampons in anymore...?

Over the summer, i used a tampon for teh first time and even though it took a few trys i was finally able to get it in. But now whenever i try to put in a tampon (using the same type/brand/size, It's painful and the applicator wont go in all the way. Im relaxing and all but i just can't get it in all the way. I really need to be able to get one in because im going on a cruise next month and its going to be around thiss time!