Acid reflux and hard stone like pellets in poop: 10 weeks old baby

Hello everyone,
I'm Jamie. I have a 10 weeks old boy who's had acid reflux for the past four weeks. I have tried zantac but it's failed. My son throws up a lot after eating when we lay him down so we have to hold him about an hour after he finishes breastfeeding. He's only breasfed, no formula. Lately the vomit is very thick. I also found something very disturbing. His poop has these hard stone pellets in them. I felt the pellets. They are stone hard. I've been to the hospital several times but nothing is helping and I need to try homeopathic remedy. He always has nasal congestion and I use saline drops to try and help him. He used to choke on his vomit a lot and even vomit through his Nose. Now we hold him all the time so his symptoms don't re appear. One Dr gave us probiotics but it's not making much difference. I'm worried about the pellets in his poop, vomit gotten thicker, straining really hard to poop and making choking sounds when we lay him down.

I would really appreciate any help please. Thank you so much.