I want health insurance, but I have had nothing wrong with me in the past. Now I think something is wrong with me, how do I get on health insurance?

Health insurance. The way the system works is this. If you have previously seen a doctor for what you suspect is wrong with you, and s/he has made a diagnosis, then you would have a "pre-existing condition". If you've never seen a doctor for this, then for insurance purposes you have no pre-existing conditions and should be eligible. Having symptoms is not the same as having a disease.