Hi - What you're describing can be caused from a few things - swim bladder, which can in turn be caused by a few things (eek!) - it can be caused by the way a fish' body is made up, and just genetic, because the body shape of the fish doesn't allow the s.b. to be shaped correctly - and also it can be caused from constipation from overfeeding, which will expand a fish's belly and cause it to make the s.b. not function properly.
Stop feeding him for a few days, then try the shelled pea method.
If the combo of taking a few days off from feeding and the pea doesn't straighten her out, your s.b. problem is from a bacterial infection and will need to be treated with meds.