Several common repetitive stress injuries in office worker, retail, restaurant and "hand heavy" jobs are carpal tunnel syndrome, tendinitis/tendinosis, ulnar nerve entrapment, and thoracic outlet syndrome. There are more, but these are the most common.
I've had all of these myself when I worked full-time at offices. They are serious business. Here's why. These situations can progress from completely treatable to permanently debilitating. With carpal tunnel, surgery may be recommended. Because you probably want to keep working and being able to use your arms for other activities, it's imperative that you go in to get help ASAP with me or with someone who knows these conditions.
Signs of repetitive stress injury can include: numbness, tingling, pain (especially radiating pain), reduced range of motion and weakness anywhere from your neck to your fingers. Isolating what kind of repetitive stress injury is a little more complicated. There are specific tests for each but there can be a lot of overlap in symptoms. Surprising to most, these conditions can also exist simultaneously - this is called double crush or sometimes multiple crush syndrome.
All of these conditions relate to nerves being trapped in areas of the body that have gotten tighter, due to tight muscles, adhesions in fascia, inflammation in the tissues, poor posture, and some seemingly unrelated things like swelling due to pregnancy.
These injuries can be treated though it may take a while for the tissues to fully heal, once the cause has been addressed. They can also be prevented to some extent through regular massage, stretching, and changes to your work station, sleeping position, eliminating similarly aggravating activities, addressing hormonal imbalances that cause swelling and inflammation, etc.