Hi,
I had similar symptoms after I apparently slipped a disk in my neck, which was already having problems due to degenerative disk disease -- during physical activity, I felt a sudden sharp pain in my neck that immediately went away but was replaced by severe pain in my thumb. Over the course of time, the pain spread to my hand and then eventually affected my entire arm. So I too think you should have your cervical spine checked. Definitely, you should see a doctor.
In my experience, if this pain is nerve root pain from your neck, it may do no good to try and treat your hand or arm where you feel the pain, and OTC pain meds might not help as much as one would hope. Try applying ice or moist heat or both to your neck, instead, to see if this lessens the pain in your arm. I've also found that regular X-rays do not always show a herniated disk, but that an MRI is sometimes required. Just my two cent's worth from somebody who has been there, done that.
Hi There,
There is a strong possibility of cervical disease like disc herniation or prolapse or cervical spondylosis.
Make sure you have good posture while sitting, do not bend forwards and do some gentle neck exercises. OTC pain medications like Tylenol will also provide relief.
In the meantime please schedule an appointment with your GP and get a clinical evaluation done along with X ray of the cervical spine.