If you are having Migraines, there are many great medications that help prevent and many that help treat the pain and nausea. You don't have to suffer! Before my Migraines were diagnosed, I was having the same thing you are: pain, nausea, sensitivity to light and sound, and also my hands would shake and I would fall on the ground because my legs would give out on me! I took Topamax for a number of years to prevent them, then changed to Gabapentin. You should start a journal to keep track of your triggers. Many triggers are stress, lack of sleep, Aspartame and food additives.
When I get a migraine, I take Maxalt or Zomig to break the pain cycle.
There is hope. Don't give up!
I am so sorry you are going through this. Did your neuro give you any ideas of what it could be at all. I know that some neuro issues take time to get a dxs. But they should have given you at least a plan and some ideas of what to do to make the sxs be a bit easier to handle.
Many auto immune disorders can cause these sxs. Have you tried doing your own research? I would also start keeping a journal of your sxs and when they act up and maybe even what you eat. What we eat can feed into how our body reacts. I wish I could be more help, and if I think if anything else I will make sure to post. Good luck and may God be with you.