@Afraser may be able to offer you advice about an excess of fluid as she had a similar problem.
So sorry you've joined us, and that you're having such a difficult time of it at the moment.
I knew I needed to overhaul my diet when I was diagnosed and immediately asked my oncologist for a referral to a dietician. My GP drew up the plan that enabled me to get subsidised visits, and I'm still seeing her today. And she is more than happy for me to eat almonds! No more Dr Google... save your sanity!
Let us know how you get on at the onc @Scoops, and keep concentrating on one foot in front of the other, one day at a time. Big hug, K xox