infant reflux? what were the signs?

My 3 week old has been having weird symptoms and I don’t know what it could be. Someone told me possibly silent reflux? It isn’t all the time that he is like this, but some nights/days he screams and cries so bad like he’s in pain and arches his back. He will do this even if he has pooped, burped, has a clean diaper on, and has just eaten.

Recently, he’s been burping a lot more even after it’s been a 2-3 hours since feeding. He has been sounding congested(thought he caught the cold my 3.5 year old had) and I tried to suck the mucus out and there was absolutely nothing. I decided to try using some saline drops to try and get some mucus out and still nothing, so I’m thinking maybe it’s fluid in the back of his sinuses/throat. He also gagged earlier and I thought that was completely odd. Are these things signs of reflux and what do they do for this? I really hate having to give such a tiny baby medication, but I also don’t want him to be in pain.