I Have A Few Questions Urgency: Not Really Just Curiosity

I have a few questions
Urgency: Not really Just curiosity
Pain: 0
Male 20



Q1► Can a person be immune to Mrsa, mono, or staff?
- Has there been any documentation of it?
Q2► If I had got a splinter and thought it was gone but latter I discover a small callous
what would be this callous be?

Skip to======== Q4► If you already know what it is
Q2 ♦Background--- had one before Chem/bio teacher bot said looks like puncture wound and probly have a piece of glass metal or wood stuck in there
First occurrence few years ago
Happened after handling wood (clean dry; doing construction for a play set)
Size of callous pea or BB
Time lasted: 3-6 months then it was gone
What i did to it: tried cutting it out my self or cutting off the entire callous Latter Used as cushin when i started guitar


Current occurrence
Time: 1-2 weeks
size:No bigger than diameter of a grain of rice
Occurrence:Helping an elder art store owner handle heavy wood (like the wood you buy at home depot)
What i did to it: nothing aka leaving it alone


========!!!!AGAIN this is just curiosity not real distress
Q4► what would cause one nipple to be slightly larger than the other for a short duration of a few days maybe a week with slight sensativity and then go away(this may be a too vague question
the nipple that was bigger is on the same bicep that is bigger (muscle imbalance due to poor workout form)
- irregular sleep pattern
- Tight shirts possibly + below suggestion
- did not work out but once and problem only showed up 4 days after work out
-Dumbbell Bench press ( milk juggs)
-Problem has gone away