My housemate sometimes acts strangely

My housemate told me she would sometimes do something strange due to a rare disorder. She would sometimes be exuberantly smiley and talkative while sometimes unusually cold and aloof, e.g. expressionless with one/two-word responses when greeted. It somehow causes me self-doubt on whether I have done anything wrong.

That sounds like she might be suffering from something like Bipolar Disorder. Given that she's told you that she has a condition which causes this behaviour, why do you still feel that you've done something wrong? It's about the chemicals in her brain. You don't factor into that.

She has EDS giving her a range of physical conditions, including asthma. Last time she cleaned the house on her own she got bad asthma attacks that turned into a chest infection keeping her home for a week. After that I agreed to clean the house for her at least twice a week - so far I enjoy doing housework and would like to learn better techniques🤣

OK. And knowing that, why does "it somehow causes me self-doubt on whether I have done anything wrong"?

I am not sure if bipolar is associated with EDS

That's not the question I'm asking. You started this thread by describing how your flatmate behaved, and I took a punt that it might be bipolar disorder. Clearly I was wrong, as you say it's EDS (which you omitted from the original post).
You said in the original post that their behaviour "somehow causes me self-doubt on whether I have done anything wrong." My question is why would you feel like you did something wrong, given that you know their behaviour is caused by a diagnosed condition?

I also act like this sometimes especially when going through a hard time and in the past it has caused my housemates to also feel like you have and wonder if they've done something wrong or whether I disliked them. Just think of it of them having a bad day. Try not to be in your head too much because you never know what someones going through in private. Maybe just asking them, checking in if they're ok is something that might be helpful for you both to clarify.
I'm personally now more aware of my actions and even if I don't want to greet my housemates or be sorta cheerful I try to at least say 'hi'. I'm lucky enough to now live with people who do their own thing so it suits my lifestyle better. I know some people prefer to have more sociable housemates but if this is the case with you, maybe its better to find that source else where. For some people home means having that private time with no social stressors, a recharge time. So don't take anything personally!

Is the following an actual symptom of EDS?
"exuberantly smiley and talkative while sometimes unusually cold and aloof, e.g. expressionless with one/two-word responses"