I really hope that the manage to tweak your immunosuppressants so that you get just the right balance between the GVHD and the graft-versus-myeloma effect. I guess the doctors are having trouble finding the right balance, and that's been hard on you. But you've got an experienced team helping you, so I'm sure they will find a solution.
Good luck. We're all pulling for you and wishing you all the best. As Mark says -- lots and lots of positive energy rays are being sent your way!
