Why am I always so tired?

Anyone can relate to this? I’ve been feeling tired, lightheaded for few years now. Been to multiple doctors, they thought I was anemic but my results came back normal. Sometimes I get nausea too. I don’t get it. So tired of feeling this way. My sleeping schedule is messed up but not sure if this is the reason behind it. Of course every time I google it, it comes down to cancer or other deadly disease. Can it be a reaction to mold? I moved into my husbands house 3 years ago and started experience these symptoms shortly after. He gets them too sometimes. He said there might be mold underneath the carpet because it was flooded at some point. Either way we are moving next month. Hope this helps.