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.
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.