Could only two things be making my credit score so low?

I had two medical bills on my credit report. I paid off one that was $238. Transunion shows that I paid it off to $0. Equifax still shows the whole $238. Then the other bill is a $40 medical bill. Those are the only two things that Equifax and Transunion are showing me. Could those two things be making my score low? It's around 552. Also, I just tried to dispute one of the reports with Equifax, but then they started asking me questions like, “Your file shows that you may have opened a loan in 2011 with whoever”, “What were your total monthly payments?”. I selected NONE OF THE ABOVE for all of those questions because I've never had any type of loans, mortgages, credit cards, etc. But it told me that the answers I entered don't match my file. Does that mean that someone opened up some stuff using my identity? Even though I don't see anything suspicious on my credit report. I'm using credit karma.

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