This is a good question and a common problem.
We just discussed this yesterday in our Caring for Photographs Online Course. You can find a transcript of the webinar here: http://www.connectingtocollections.org/courses/caring-for-photographs/ and we will be posting the recordings of the webinars in a few weeks.
Unfortunately, if you try this yourself, the risk of damaging the photograph is high. We recommend that you contact a conservator. You can locate a conservator with a specialty in photographs by clicking on “Find a Conservator” on the American Institute for Conservation website (http://www.conservation-us.org). While storing the photograph in the frame may not be ideal, it may be your best short-term solution. Can you remove any acidic materials that may be behind the photo and replace it with archivally safe material? Is it possible to scan or photograph the item so that you can use a copy while you store the original?