Aspartame causing pain!

I have been drinking a naturally flavored sparkling water beverage containing aspertane and after a lot of research have found that others have experienced pain such as associated with fibromyalgia even though I am taking 1,000 mg of vitamin D3 daily but do not know if I am deficient in magnesium so I need to tell my doctor to order tests.

Would that be the problem with my pain which is in my shoulder/arms? My doctor has given me Meloxicam 7.5 mg and told me it is from RA but Ihave no symptoms in my hands or any other parts only shoulder/ arm pain. I did have some pain in my neck but thru exercises from my Yoga instructor the pain has gone but I am trying to detoxify my gut to get rid of the aspertame and have stopped drinking the beverage and am checking and getting rid of all items that contain it from my pantry.
Thank you,

Jane