Pimple vs Cold sore vs Chapped lips

Hi,I know you have had similar questions,but I can't seem to find any that have my exact symptoms.

Last night, a little after I ate dinner, my bottom lip started itching reallllly bad. It felt like a bunch of needles were poking it, so it kind of burned, almost like I rubbed chili powder on it. Right in the middle, this small white bump, maybe 1mm in diameter, appeared, and it itched too. It got bigger when I kept scratching/rubbing it, and then later that night,it was no longer there, but the entire area around it was red and my lip looked weird.

Today, the bump is back and really tiny still, and it kind of itches but mostly is just makes my lip feel funny.

I've always had pretty bad chapped lips, but as long as I keep applying chapstick on a regular basis, they are fine, so I don't know if it is chapped lips.

I was eating chili last night, but I eat it all the time and have never had a problem, so I don't think it is allergies.

However, about a week and a half ago, I accidentally grabbed my mom's toothbrush instead of mine (they look exactly the same) and used it once at night, when she had used it that morning. The problem with that is, she suffers from cold sores or HSV-1, whatever you want to call it, and I'm afraid I might have gotten that and now this is a cold sore. The problem is, I've looked all over the web and what I have does not seem to be a cold sore, especially since there is  only one small bump and it isn't getting bigger.I take good care of my skin, so I don't think it is a pimple because I don't have pimples anywhere near my mouth.

I don't want to go running to the doctor's office yet, but I would really like to know what this is, because if it is a cold sore, then I don't want to perform oral sex on my boyfriend, or even kiss him for that matter. Please help me!
Thank you!

[Bhupinder Kaur, MD]

Hello,
Given your past history of using your mother’s tooth brush, so the possibility of cold sores cannot be ignored. The diagnosis of cold sores is usually based on the appearance of the lesions. For confirmation, a variety of tests are available, including viral culture and polymerase chain reaction(PCR). My advice would be to consult a dermatologist.
I hope it helps. Take care and please do keep me posted in case you have any additional doubts. Kind regards.