Without having been seen by a neurologist or doctor who deals with MS, it would be difficult to offer an opinion on MS. There are many possibilities including neurological concerns.
Have you seen a cardiologist to make sure it is not heart related? You can filter through much of this with your GP who would likely do blood work and a CT. You need to be able to ascertain whether it is a physical problem or a neurological problem. Once that fork in the road has been reached, then you can get closer to resolving your situation.
If you need a neurologist, make sure you see one who specializes or handles many MSers because you will learn to appreciate that doctor's experience. If you do not have one, ask for a referral or contact the MS Association or Society. Either organization can readily assist you.