What Causes Elevation Of MCV/MCH Levels And Being On B12 And Effexor XR?

Hi, I have had elevated mcv/mch and hematocrit for several moths now. Seemed like an issue with b12 would have made sense, but after taking supplements my b12 is actually now higher than the normal range. I experience achy muscles for no apparent reason, feel easily tiered, and like I sometimes sort of "sigh" in order to get more breath. I also experience intermittently itchy arms and legs with no rash. I do take Effexor XR, and have been told these could be side effects, however I have read that high MCV/MCH usually means something? I don't drink alcohol at all, have not for 4 years, as I did have issues with that previously. Liver and kidney tests are all good. Any ideas? Do I just have high numbers as my regular baseline? Thanks! - fiona