Ah I know where you're coming from with this! We had the same thoughts and feelings with our son in the early years. Thankfully he's a bit older now but anytime he gets sick or has something going on (unless it's self inflicted because he didn't listen to me to not run around like a monkey in the house lol) I always feel bad that I can't take the pain for him. The difficult part mentally about that is that we can't but the important thing for them is that they feel these things. It's important for growth and development of their little brains and bodies, as difficult as it is for us as parents to witness it.
Teething was tough! With some of the teeth, our son broke out in crazy fevers. His molars he was at like 104 it was insane! Those were incredibly long nights for me, I barely slept checking on him constantly and trying to bring his temperature down with tylenol and other things.
The kids being sick isn't fun that's for sure but it's important for their bodies and immune systems to get it. This whole notion of the past few years that being sick is a problem is foolish! Our bodies come into contact with respiratory viruses and other bacteria constantly so we are bound to get sick. The important thing is to give our bodies the tools it needs to fight it off like lots of water and other good nutrients!
Feel free to post here any time you want! :D I may not get to it right away, as I'm getting to this one 2 days later, but I will get to all of the posts I haven't yet seen or commented on. I appreciate you coming to the community here to drop some thoughts :D