I can't be sure of the source of your pain, but I can say that when my breast cyst was responding to iodine, it became much more tender. Sort of a wake-up call. It resolved only very slowly, but it did resolve.
I think painting your abdomen with 5% Lugol's is an excellent idea and should move the cyst resolution forward. Give this whatever time you can while still honoring what your inner voice tells you.