I am sorry you are feeling so badly. It is frustrating to feel so badly and yet tests come back normal and the Drs don't know what is wrong. Keep investigating. Your symptoms are not normal.
Another thing to check out that has similar symptoms to MS is lyme disease. Lyme can be very serious affecting the central nervous system as well as every organ in the body.
If you check out lyme please know the bloodtests are only about 60% accurate. The bacteria (lyme) evades the immune system and you do not produce antibodies and that is the reason the tests are inaccurate. The best lab in the country for tickborne diseases is igenex in Palo Alto, CA. Any Dr can sign for the test.
BTW shortness of breath is a classic symptom of babesia, which is a co-infection frequently found with the lyme bacteria. A large percentage of people who have lyme have atleast one co-infection (there are several)
If you do a google search you will find lots of info. Any questions just ask.
Best of luck to you.