Pulmonary Embolism Support Group
By far the most common form of pulmonary embolism is a thromboembolism, which occurs when a blood clot, generally a venous thrombus, becomes dislodged from its site of formation and embolizes to the arterial blood supply of one of the lungs. Symptoms may include difficulty breathing, pain during breathing, and more rarely circulatory instability and death.
There are several people on the DVT group who have had blood clots in their arms. You might consider posting there with this question, or just searching for previous threads.
I've had an arm clot. It wasn't red or swollen; it just hurt, and the pain wouldn't go away. I would be inclined to think you were ok with your INR therapeutic, but if it continues, gets worse, pain starts crawling up your arm, you may want to call your doc and have it looked at.
Also, remember to stay well hydrated. Lack of fluids can cause all kinds of muscle and cramping in both our legs and arms.