Could One Swollen Tonsil Be Nothing?

I'm sorry for cross-posting in ent and cancer forums, but i'm not really sure where this should go...

Three weeks ago exactly I woke up with one enlarged tonsil, on the left side. Upon further examination I discovered that the swollen tonsil was covered in little white spots. My first thought was that it must be the beginnings of strep throat (which i've never had), but it seemed odd to me because I didn't feel any pain. I scheduled a doctor's appointment that very day. After examining me, the doctor confirmed there were little white spots on both tonsils, and mildly swollen lymph nodes my neck. He told me it must be either a strange case of strep (because I felt no pain), or a strange case of mono (because I wasn't feeling exhausted or otherwise ill). He gave me a blood test and a prescription for a 10-day course of antibiotics (penicillin). He called me the next day and told me that the blood test had confirmed it was neither mono nor strep, but to keep taking the antibiotics and schedule a follow-up if they didn't help.

After my ten days of penicillin, there was no real change except for the fact that the little white bumps are gone. The tonsil is still swollen and painless. I'm not very self-aware when it comes to my body, and can't tell whether or not my lymph nodes are at all swollen at this point since I don't know precisely where they are. I scheduled a follow up appointment, which is happening in a couple of days.

I've done a lot of internet research over the last few weeks, and quite unfortunately there don't seem to be many things that cause one swollen, painless tonsil. It's pretty much tonsilitis, tonsil stones, hiv/aids or lymphoma, according the every online resource that exists about the problem. It's not tonsilitis because it's caused by strep bacteria, which the blood test confirmed is not my issue. I ruled out tonsil stones because the white spots weren't hard or large or smelly, and eventually they went away. I'm not promiscuous or an iv drug user, so i'm praying it's not hiv - however, I can't rule it out - I have had unprotected sex twice - once in a monogamous relationship, following sti/hiv testing for both me and my partner, and once about a year ago with a trusted friend who's sexual history included at that point only two monogamous relationships and the occasional tryst with me. (i am going to be responsible and ask for an hiv test at my follow-up appointment.) that pretty much leaves lymphoma, which is a really unfortunate option - but it seems silly to think this could be cancer when I feel more or less fine otherwise.

I'm a 24 year old female non-smoker. I'm overweight and don't have the best diet or exercise habits, but other than allergies and asthma, i'm generally healthy. Other than the tonsil, the only change in my health lately is the fact that my allergies (dust, pollen, etc.) have been really bad, to the point where i'm not sure my allergy meds are working very well anymore.

If anyone is still with me after all of that...Has anyone experienced something like this? If so, what did it turn out to be? Could some random virus just happen to affect just one tonsil and not the other, and otherwise be asymptomatic? Or is there a chance that it's really nothing at all, and my tonsil is just being stupid? I just need a little reassurance so that my hypochodriacal tendencies don't get the best of me and send me into a tailspin as I wait for this next doctor's appointment.