Oh my goodness. She MUST get to a hospital. Why would her doctors allow her to leave with a level of 6.4??????
I came across this looking up low hemoglobin. I recently had a blood transfusion (my hemoglobin reached 6.2). I had passed out, having flu like symtoms - was in the hospital at the time it was lowest and I don't even remember signing a waiver to get a blood transfusion. Eventually found out I had contracted an infectious strain of C. Diff - it's terrible and don't wish it on anyone. If you're wife is constipated it's safe to say that C. Diff is not her concern, but she is NOT getting enough oxygen to function.
The low hemoglobin would also explain mood swings. She likely has a hard time standing, carry things, focusing, or just living her life. She may be skeptical about doctors and there could be a reason she feels that way. However, if she is not able to find the source of the issue and her levels drop even lower, she WILL end up in the emergency room at some point - best case scenario. She's already in a critical state. When a person has low hemoglobin, your sense of judgement disappears - it's like being drunk. (DO NOT LET HER DRIVE!!!!). They released me from the hospital after 5 days b/c they didn't find out what was wrong in my scenario....my hemoglobin was at 8 something when I left and I got a speeding ticket on a street drove every day. I didn't even know where I was.
I'd offer a suggestion of letting her know that you care and want to do whatever you can to help see that she is healthy - immediately. Set up an appointment, fill out any forms ahead of time and bring her there. Take the weight off of her shoulders - she probably can't even deal with filling out paperwork b/c it seems too exhausting.
This is coming from a 31 yr old female who ran marathons until a few months ago ( I'll be able to do them again even by fall after being on the medications to heal :)). Experiencing what it's like to only have half of your oxygen supply, I understand that she is only half alive right now. I hope to see a post that that everything works itself out! :)