@DebraDownSouth:
Also, just wondering if this is ONLY when laying down. First order, even before a behaviorist, is a thorough physical exam and blood work to rule out pain or disease, hip dysplasia, thyroid, etc. That it only seems when laying down makes me wonder if she is really hurting.
It couldn't hurt to have her medically checked, but since she is only 5 mos, she has probably seen the vet fairly recently…and while she may have any of the above problems, it unlikely that she would express any behavioral symptoms related to health at this point.
IMO she is simply pissed off that someone is forcing her to do something. She is being a dog, with poor bite inhibition...some dogs bite when they don't want to do something, and as we know (having basenjis) trying to force them to do anything the don't want to do is, at best, fruitless, and at worst, dangerous.
If the OP got the dog from a responsible breeder, hopefully he or she can help, but not every breeder is knowledgable about changing undesirable behaviors. But either way, the breeder will want to know if the dog is having behavior problems.