Most sexual identities are the product of a certain balance of hormones and other various chemicals, but nisexuality is definitely not a healthy state to be in. It sounds like you have a serious deprivation of testosterone (I am assuming you are a male), which can lead to depression as well as a decreased sexual desire.
This is not to say that it is unnatural to not feel sexual attraction, as men do lose testosterone as they age, but it is often a sign that things are not quite right. I do wonder what the difference is for women, but I am aware of the effects for men thanks to sexual education.
If you are experiencing symptoms of depression, then I suggest you find a doctor who can help you with that. If you don't feel comfortable doing that, then, at least, schedule regular outings/walks in nature, taking the time to take in the scenery and breathe. The air in the house, even with the windows open, grows stale and can even deprive you of energy, which doesn't help when suffering from depression. That said, I'm not an expert on the subject, but I have dealt with a similar situation where I broke it off with my girlfriend because I couldn't feel any sexual attraction towards her or anyone else.
Considering this is a new feeling, it's very unlikely that this is natural.