When I used to work out I'd sometimes get a deep sore feeling in arms and legs and even slight pain. It was similar to the feeling you get when you have buildup of lactic acid but not quite. Could this be associated with the loss of muscular mass, nerve compression or simple stress? I'm curious to have some answers as I'm certain some of you have experienced this to some degree.
Sounds like simple muscle soreness, depending on your health level, amount/intensity of your workout and your hydration level - it could all be normal. Everyone has a different level of pain threshold and different ability to recover. You need to create/modify your workout program to accommodate your current health level, your ability/need to recover and what you're looking to achieve. The most important factor is creating a program that will keep your interest long term. Stay hydrated and keep at it!
I finally found the source of this soreness. It's actually linked to vitamin D deficiency. This vitamin is normally synthesized when you expose yourself to sunlight. You can get some capsules as a Chemist's and it should be possible to spot the issue with a GP. In Western society the deficiency can still appear though and can affect calcium intake (possible explanation for early osteoporosis). Additional symptoms can include also sorness at the joints and hips. Here is an informative link on the topic.