Jaw pain and arm pain for over a month now, ended up in a&e had bloods and an ecg, they and my doctor said it wasn't my heart, but i'm terrified it is?

Doesn't sound female: Your symptoms for heart problems sound more like a man's than woman's. Most women's symptom are a feeling of indigestion or heartburn. Did you do any heavy lifting or slept in a funny position. Does the pain go away with meds like ibuprofen? Look at what you may have done to tweek your muscles on that side. Perhaps lifting a child or pet could do that. Don't live with it and get second opinion.