My new clothes already don't fit

A couple weeks ago my friends and I went to the mall to get new clothes and I got a pair of jeans. I put them on this morning and they are huge? I can fit both of my fists in the waistband... (These aren't stretchy) And I can't return them since I've already worn them. The shirts I got as well are also starting to look a little baggy, even though they looked more fitted when I got them. :/