Hello there,
I have actually been dealing with a similar thing the last few months.
I have a fistula on my upper arm. They had my flow rate always set at 500 because I could always handle it & I would always clear so well. Within the last few months my arm would start to ache & get sore with pain. I never move my arm because I'm always scared I might ruin my fistula if I would infiltrate it. Last month they scheduled me to get my fistula looked at, I thought for sure they would have to balloon it open & clean it like they do every year or two. Well I had the procedure done but they weren't able to find anything, they said my fistula looked excellent!
I was very happy to find out that everything was ok, but still a little worried as to why I was having pain during treatment in my arm. Then pain would get so bad by the 2nd hour that my BP would start to drop & they would have to take me off the machine early.
Anyway... They lowered my blood flow rate to 450, instead of 500. I still clear well & was able to still keep my 3 hrs without them upping my time.
My arm no longer hurts like it did & I am able to tolerate everything!!!
They told me they think because my fistula is so big & having the flow rate that high was taking away blood flow to the lower arm & causing me pain... whatever the reason, lowering my flow rate helped me!
Good Luck
~ Marna