You are saying you went to Urgent Care, and you were "unable to be tested" (I assume you mean, for Covid), and you didn't just go to the drugstore and buy a test kit? They are available all over and cost less than a visit to Urgent Care. I ask because it would be helpful to have ruled Covid out, for the purposes of wondering now what you had then. (It really sounds like Covid.) The fact that Urgent Care was OK with just writing you a scrip for an antibiotic seems odd, given that medical practice is not to over-prescribe antibiotics due to antibiotic-resistant bacteria problems.
Anyway, given where you are now, which is feeling better and being sure it was bacterial, all you can do is try to run down where you might have picked up something bacterial. It could have been a secondary infection that arrived because you had a virus, that happens a lot with viral infections. It could have been from some kind of bacteria in your environment. Doesn't sound like Lyme disease due to the lack of a rash. Any small injuries or punctures to the skin at that time?