Moved this into the RTB forum for ya. I'm not as familiar with boas as I am pythons and colubrids, but it probably is shed time. Just bump up the humidity some and leave him alone until he sheds out. (Can take a week or so from the time you first notice signs until they actually shed out) IF he finishes the shed, but has big pieces stuck all over him, then you may need to soak him and assist in completing the process. But until then...just let him be. Most likely he'll do just fine all by himself.