Cher:

 have you looked at mom's diet as a causitive factor in baby "clamping"?

 has mom tried "dancer hold" to support chin... some babies clamp when they
have trouble maintaining hold..... another thing is to lean mom back ....

  what state is the baby's mouth? is she/he "itching"   his/her palate from
thrush causing clamping ?

  deep seated thrush can take some time to heal...

          Patricia