There is the possibility of being sued for fraud. To be fraud, the representations must be false (or facts were concealed), and you know they are false, which you admit. You also have to intend to deceive the other party, which is the case (you didn't say "I accidentally made up a name"). The representations also have to be material, and that part is hard to judge; the other party has to rely on those representations, and they have to be harmed by that reliance. I will assume that both parties are adults (you're not 16 pretending to be 21), and that neither party has HIV (disclosure of which may be required by law). Your vague mention of "health" does, however, raise a red flag: I assume you are referring to undisclosed gout, or something like that.
There are very many scenarios that we could cook up whereby you would or would not be liable for fraud. For example, you are more likely to be liable if you have falsely implied an intent to marry the other person (assuming that was a material consideration for the other party). Whether or not any harm occurred would, again, depend on the specific facts (as revealed through testimony).
In some states, "rape by fraud" is a crime, for example in Alabama where it is the class A misdemeanor crime of sexual misconduct if you
Being a male, he engages in sexual intercourse with a female without
her consent, under circumstances other than those covered by Sections
13A-6-61 and 13A-6-62 ; or with her consent where consent was
obtained by the use of any fraud or artifice; or
In Idaho, it may be unqualified rape
Where the victim submits under the belief that the person committing
the act is someone other than the accused, and the belief is induced
by artifice, pretense or concealment practiced by the accused, with
the intent to induce such belief.
If you are actually concerned, you should talk to a lawyer and reveal the details that you don't want to talk about here.