12 mths old really sick

Hello doctors
My son started vomiting vigorously at the age of 5 months. He used to vomit first thing in the morning. at first it was diagnosed that he was lactose intolerant, for he was mostly bottle fed back then. He was almost partially breast fed for the first 6 months as i lactated little this time (he is my second baby). I stopped everything with even an ounce of milk in it. It worked for like couple of days, during the period of which i used to give him thinned khichri, oats etc. After that he started vomiting at the sight of food. Then our homeopath advised that he had a weak constitution. I dont exactly remember what medicine he gave, but he stopped doing that (vomit at sight of food) after some days. He still used to vomit for like 10-12 times a day, which is every time i tried to make him eat anything. He would either vomit during eating, or after 10-15 mins of the feed. The vomitus was only food. Nothing acidic. The whole of the food and something more whatever was in his stomach. He used to gag even at the taste of an empty spoon. I'd just touch the tip of the spoon to his mouth and he would gag vigorously. Sometimes formula milk used to stay, which was a big sigh of relief. But not every time. I then sought a pediatric, who said he has a small esophagus, and he will be like that for at least a year. I carried on with my homeopath then. I think these kinds of problems are curable in homeopathy than allopathy. After that he has been given a series of homeopathy, with not much result. I dont remember all the names, but some were, Lahchesis 200-1m, Colchicum, ANTIM TART, Arsenic iod 200, then once he got high fever and cold, thats when the doc advised Opium. The vomits were reduced to 1-2 after Arsenic, but not gone completely. And after Opium, the symptoms are back. He has always been given the medicines on the pulse of his right and left hand. Except once, when Arsenic was given for the first time, I gave it to him 3 drops diluted in water. My doc would never let me repeat it after the first dose.
My son is not much of a eater. He is apparently under weight. If i give him anything thicker than the consistency of water, he vomits at the first spoon. And anything granular is also a big no no to him. Only milk is something he is able to handle.

He walks, but falls a lot. Anyone can make out that his legs are weak. He keeps waddling and bumps left/right.
He is never really really hungry. There are days when he doesnt ask for food for like 3-4 hrs. And when i try to feed him without him asking, undoubtedly he vomits. Although he is quite an active baby, he is only 8.5kgs now. Sometimes he vomits first thing in the morning. There is not much vomitus, but the milk (which he has had through the night) is curdled, very thick and smelly. The process goes on for like 5 mins at least. Nothing much comes out really, but he gets recurrent spasms in the stomach and is not able to breathe. His face turns red and nose starts running post vomit. Its a truly pitiable sight and only God knows how difficult it is to watch my baby in pain.
Last week he had severe cold and fever. Thats when he was advised Tarantula 200. There has been very little improvement in his cold, and his vomits are still the same...1-2. Pls note that its not the normal vomit babies usually do. Its the WHOLESOME food that comes out, during or right after feeding. I am really desperate now. Pls advise something for his overall constitution and weight gain.
Thanks
Farheen
Mumbai