An enlarged spleen is also the symptom I went to my GP about before my CML diagnosis. White blood cell count at that point was a whopping 620 so I was prescribed Hydroxycarbomide, a chemotherapy drug for four weeks to stop the over production of white blood cells before switching to Imatinib. My spleen had already shrunk quite significantly before the end of the initial four weeks and the discomfort stopped then.
If your counts sound similar but you weren’t given the initial chemo (don’t panic, there was no hair loss) then maybe that’s a conversation to have with your consultant?
Sorry I can’t help with the pain as I’ve been really lucky and never had anything more than mild discomfort.
Best of luck on your journey :)