MCV and MCH values low on bloodwork



I posted this in the trt forum,but wanted some more thoughts on why these values might be low. One of the things that popped up when i googled it was vitamin b6 deficiency or low iron. My rbc was high,as it usually is on trt and hemoglobin was not. On my last bloodwork my MCV was 90 and this latest bloodwork it was 78. My MCH was 30.5 last time and is now at 25.6. These numbers have never had a change like this in the last 3 years. I did have a hernia operation in may,and took a very small dose of var (5mg per day x 4 weeks) to help with recovery. These are the only two things different since my last bloodwork. So I started taking a b6 b12 sublingual in hopes of that being the fix. Anyone got any ideas at all about why these numbers would change? Both draws done by same lab. I had originally posted this in the Q&A forum with no response,maybe someone here can help.
Thanks