What Causes Difficulty In Swallowing While Suffering From Multiple Sclerosis?

I have been diagnosed with MS 14 years ago. My symptoms began with swallowing and speech difficulties. My latest speech,swallowing test indicated that my palate is severely impacted, collecting liquids that go very close to my trachea. The therapist indicated that she felt more neurologic testing should be done. I ve tried to contact my neurologist, but to no avail. I am going to try to see about a palate lift . Do you have any suggestions as to what may be going on. For MS, my right leg is weak and sometimes drags and I have optic nerve atrophy in both eyes, more in my right. Prior to MS diagnosis, I went deaf in my right ear but was brought back to almost 100% hearing with steroids.