Hi there!
The backache, decreased perception and loss of sensation in the arms are likely to be three separate issues. While backache issues could result from postural, spinal/ structural, neuro-muscular issues etc. ; perception issues could result from hypoglycemia, nutritional deficiencies, high or low blood pressure, neurological issues etc; while loss of sensation could occur from nerve trauma/ nerve compression, neuropathies (primary or secondary to causes such as endocrinal/ metabolic issues, micronutrient deficiencies etc), a few infections etc. It would be best to get these evaluated by a primary care physician initially and depending on the causes diagnosed/ suspected, these can be treated accordingly or specialist care may be sought.
Hope this is helpful.
Take care!
I would also like to point out I am an athletic build 27 year old male with nothing that would indicate what this is caused by in my history.