I Am A 65 Year Old Woman On HRT Pellets.

I am a 65 year old woman on HRT pellets. I am taking 2.5 mg progesterone and have not had a problem in the past. Ran out of progesterone right before my last pellets and took a couple of nights of 20 mg I had left from before. Started spotting. After my pellets were installed I have bled for over 3 weeks now. Dr wants to put me on norethindrone. Is this necessary? Is there anything else I can do? I prefer to not take meds if it isn't necessary.