Which supplement?

Anyone know which supplement is best for allergies? Ive been giving Bailey missing link for about 2ish months now and it has helped alot with his allergies. He hasnt been licking the nakey spots on his belly at all (thats usually where he gets all itchy and lick it till its raw) and his ears havent been bothering him either. Im almost out of the missing link so i have to get more for him soon. I want to get the best for him cause he seems so much better and happier now that his allergies have got better, but i dont have a job and not like my parents would be willing to help so i have to buy it myself, so it needs to be somthing i can afford. I found some fish oil caps and fish oil in a bottle while looking around online for supplements for him that arnt too expencive... are those better than Missing link? Im not really sure what to be looking for in the ingredients so im hoping one of you all-knowing idoggers can help me Smile