Here at Connect we cannot diagnose medical problems but only share from our personal experiences, I would encourage you to seek some medical attention sooner rather than later. These symptoms, might be stress-related, but they do sound like a neurological problem that needs to be diagnosed.
The fact that they come and go is perplexing and many neurological problems are hard to diagnose unless you are in the middle of an episode, like MS, Parkinson's or even small strokes. I had symptoms of a neurological disorder for many years before it was diagnosed so keep looking for answers, with a good medical team.
The numbness, heaviness, etc. that you mention warrant a call or message on your doctor's patient portal.