Hi Flower20, sounds like your Onc and GP are doing all the right things and although it is stressful waiting for scans and results I am sure you will get to the bottom of this soon. The only thing I can add is that chemo can take a long time to get out of your system and can create all the symptoms you are describing. I know because I had quite a lot of aches and pains for a long time during and after chemo. I also had numbness in toes which has now gone. Muscles and bones can cause sciatica and you may need some physiotherapy to rebuild strength in your hips etc after the chemo.
Tamixifen can also cause aches and pains so try not to imagine the worst. I know that is easier said than done by the way!!
Try and enjoy the sunshine
Suzanne x