6 weeks ago me and my colleague were sitting at the office and we had our face masks on. To take a few photos we both removed the masks (it was a Single Use Disposable blue color Face Mask).Then my colleague folded his mask and kept it on the desk. And Within 1 to 2 minutes, after he left it there, mistakenly I took his mask from the table and wear it. Within 30 to 40 seconds I realized that, I was wearing my colleagues mask and removed it immediately. I am pretty sure It was very dry. (It was on the table for 1-2 minutes, from the time he removed it and then I wear it.)

After 10 minutes I wipe down my lips and face with some hand sanitizer using a paper towel as I was paranoid (I have little OCD too).

After 7-8 days of the mask incident my face got irritated and mouth was very dry. Lips were burning and peeling a little bit and my tongue was rough(inflamed) and felt irritated. This was continuous for 2 weeks. 

I am not sexually active and never had sti issues or cold sores. Last year as a routine test I did a full STD panel including IGG test for herpes (All were negative).

What is the risk that I am getting HIV from wearing his face mask in this incident ?

What is the risk of getting any other STD (syphilis, gonorrhea, chlamydia,hsv) due to this incident?

What if If he already had Hiv or any other SIT ?

Do you think I should worry about this or get tested for STI?

If some one get covid can Hiv or other sti tests result false positive?

What if there were some saliva droplets and virus on the face mask? Can hiv or any other sti transmit via a mask?

As I had Pfizer booster 2 months ago, can this cause false positive if I do STI testing. If someone gets a hiv false positive, is there a way to rule out it in north America?

There is absolutely no risk of HIV or any other STD. Any infection risk was only for respiratory infections like COVID, colds, and influenza if your colleague was infected at the time. But zero risk for all the STDs you mention, even if your colleague had such an infection. You should not be tested for any STD on account of this event. But if you do, the answer to your last question is no:  neither the COVID vaccine nor any other drug can have any effect on the test results. But please do not be tested:  there is no possibility you are infected, and the tests are not perfect:  if positive, it will be a false result that will only increase your anxiety. Don't do it.

I hope these comments are helpful. Let me know if anything isn't clear.

HHH, MD