I feel numbness in my upper left arm, have a mysterious lump in my neck getting mri in a few days should i worry?

No: Worrying never seems to help much. As with many things in medicine, this could be something harmless and relatively easy to fix, or it could be more serious. It is important to follow through and get the MRI scan. In the meantime, try not to worry and focus on eating properly and getting eight hours of sleep a night. If you feel anxious, go for a long walk.