Thankyou for your question. Im very sorry about the delay getting back to you with an answer. Unfortunately it is impossible to diagnose something online. Your best bet is to ask your doctor what they think. When a doctor can see someone in person they can make much more accurate (or accurate at all) diagnoses. Throbbing and achy arms can be a symptom of anything from a strained arm to a heart attack to a little dehydration. The only way to tell is if your doctor is able to see you in person.
I hope this was helpful