Thanks for the additional information.
Well BGJ398 is still in trials for various forms of cancer and is still being studied regarding its side effects however the major side effect which was discovered so far was the marked increase in phosphate levels which can cause severe muscle aches and pains. This however would not be an issue if your phosphate levels were under control because of the phosphate inhibitors which you are on. If your phosphate levels are normal, then raised phosphate levels should not cause the pain. Since the drug is still being studied, not a lot is known about its various side effects however some studies have mentioned that it can cause severe aches and pains in the muscles apart from the phosphate effect.
However, that being said you need to have other causes of the pain ruled out, since you have a malignancy that would predispose you to developing blood clots in the arteries as well as the veins which in turn can cause this sort of severe pain in the legs. That can also cause numbness, decreased temeprature in the legs and a doppler ultrasound of the legs is essential to rule out this problem. Secondly peripheral arterial disease should also be ruled out here and a doppler would be effective there as well. Another cause of the pain can be compression of the nerves in the back because of spread of the cancer to the spinal cord or the bones. This can cause severe pain in the legs and a MRI and xray of the lower back can be useful here. The next best step here is to get the above three conditions ruled out which once excluded would leave the drug as rhe cause for the pain.
Now since your pain is worsening then i would suggest a visit to the urgent care center or the ER where they can run these tests as well as give you IV painkillers to control the pain. in the meantime what you can do is to add tylenol, motrin or aleve to your painkiller regimen to counter the pain but i do feel that you need to go to urgent care to get this managed effectively right now.
Do you have any more questions?
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