would help if you posted your current medic cfg to give people more information about your problem.
but you could try:
bind 1 "slot1; r_drawviewmodel 0; viewmodel_fov 90"
bind 2 "slot2; r_drawviewmodel 0; viewmodel_fov 90"
bind 3 "slot3; r_drawviewmodel 1; viewmodel_fov 90"
this will make that only your melee weapon will have model enabled.