All over twitches/tingling are not a typical ms symptom. They would more likely be due to a vitamin deficiency or anxiety. I have ms, and also have twitchig -- however it's due to low magnesium in my case, rather than being related to ms.
Your best bet is to head to your gp and get some blood work done ... things like B12, vitamin D, magnesium etc. Make sure you don't have any glaring deficiencies, but if you do, they are easily supplemented. Many, many people are magnesium deficient and have no idea because it's just not tested. Even with a healthy diet, the soil growing our veggies no longer contains much Mg so historical sources just don't provide it.
If these have been done (you do mention seeing your doctor), it wouldn't hurt to check in with a counselor either. But I'm going to hazard a guess that the vit/mineral levels weren't checked :). There is a remote chance widespread tingling would be a peripheral nerve issue (again, not ms) but I would start with the other two options first.
The neck grinding could warrant a visit to a physiotherapist with your boxing history -- might be facet joint syndrome or something -- physiotherapy will help, and again, nothing neurological about this at all :).
Not a doctor here, just someone who didn't have a dx for a while and had to figure out how to treat symptoms on her own :).
Best wishes :).