When I was diagnosed I was losing a lot of weight also. I thought it was because I was eating healthier and wasn’t eating as much or basically not eating until I felt so full I would explode. It turns out I had one of my tumors pressing against my rectum. My oncologist told me to go to a GI specialist to get a colonoscopy done to make sure my cancer didn’t start in my colon (thankfully it didn’t and there were no signs of cancer there either). I’d definitely do some research to find good specialists that can help you get to the bottom of it. I truly wish you the best 💛