It sounds like there is something in the water irritating and making him secret extra slime. First, stop adding garlic to the water. It would only take a trace to stimulate a feeding response and anything more can possibly just be an irritant plus its extra organics and nutrients in the water and that we like to keep down somewhat. Very little would be absorbed to provide an immune response directly or in competition with ick since you have more issues than just a cyclic parasite. In the food, a very little goes a very long way and a lot goes no where. Without knowing how much kalk or additives you drip in, its hard to tell. pH, alkalinity, temp and salinity are important as is the nitrite/ammonia content. Did you just get the fish? Be sure the equipment is clean and in good order. No salt bridges to anything electric to cause an electric current in the water. Do small water changes for the next 10 days if the water may be out of balance, old, new tank or anything other than stable. Look for someone to fill you in on meds. The med has to be correct for the problem or its a false hope. I never use any of them, sorry.