Maybe your feeling ways about your ex because you are dating again. Or maybe you just need to tell your ex how your feeling, maybe you'll give each other another chance, depending on the situation of both of you breaking up. But give the guy your dating now a little more of a chance before making your final decision. He may be a good one, finding true love takes time, and if you want true love, you have to be willing to wait.
I would wait until things are over between you and the guy you are currently dating before trying to find out if your ex still wants to be with you. In relationships, it's not always healthy to allow your emotions to rule you. Not to mention, if you dump the guy you are with because you are feeling like going back to your ex, who's to say that your ex really wants to be back in a relationship with you? The two of you may have a short fling, but if it didn't work out before, and he really doesn't want to be with you, you will have lost out in two ways - with your ex boyfriend and with your current one. You should wait until your emotions settle down before making decisions.