My youngest is 6mths and is still suffering with it, thankfully she is not upset by it now (as a baby she cried after almost every feed) but she is still what we call a 'happy sicky baby' !
We use gaviscon which doesnt solve the problem but she is so much worse without it, so we will carry on with it for now. We were advised to wean her early to help but I am not sure it has really made much difference!
We use a cot wedge and keep her upright after feeds etc etc but I think it will just be a case of waiting for her to grow out of it!