By applying for Social Security Disability Insured Benefits (based on your payment into the insurance program through payroll taxes), or Supplemental Security Income benefits (welfare), you are stating you have medically diagnosed condition that is so severe that it is expected to result in death, or is so severe that it will prevent your performing any type of work (not what you used to do, not what you would like to do, not what would pay a lot of money but any work) that would offer gainful employment.
This is the Social Security Administration definition of disability. It is doubtful that Vitamin B deficiency will meet that standard. Be prepared to list the frequency and severity of migraines, bone shattering pain, and IBS. A calendar listing frequency, what you were doing before the headache started, how long it lasted, and what you did to relieve it will be most helpful. If these conditions have not been severe enough for you to seek treatment don’t bother.
How does your MS affect your ability to perform work related functions? Are you wheel chair bound, do you require crutches & braces, etc.? With physician statements as to the medical need for the assistive devices your case to be adjudicated and allowed overnight.
Don’t be surprised, however, if your application is denied. Your statements strongly suggest you do not have, or even believe you have, a medical condition that meets the SSA disability definition as you indicate you quit work for reasons entirely unrelated to any disabling condition.
If you truly think you have a medical condition that meets the SSA definition of disability you should list every doctor who has treated you for the medically disabling condition(s). You do not need to wait until you have all the paperwork because you will be given plenty of time to modify your application.