Just to clear up the issues. The issues is caused by internal parasitic or blockage issues. First thing is The medications your using arent meant for this issue. They are also bad to mix as one is Erythromycin (a gram positive treatment that doesnt play well with others) and the other (Kanamycin sulfate, a gram negative primary with minimal gram positive treatment and it can be combined with specific treatments BUT you have to know what they are... Nitrofurizone, Triple sulfa, Malachite Green, Doxycyline, Formalin, Methalyne blue.... BUT they are specific.) in the case of your issue id recommend a Bath of Epsom and tank water as a relief. 1 tablespoon per gallon for up to 30 min. You can add Methalyne blue to it as an aid and it also helps add oxygen directly to the hemoglobin of the fishes blood so if breathing is rough it helps. The epsom is a two part help as a mild diuretic as well as a laxative. Your diet for this fish may be lacking in the right things and is causing bloat. I would also look at using a treatment to start with as orally dosed Metronidazole. Many of the bloat issues with fish can be cured with this and Epsom. Id recommend a food that has Metro in it or soaking the food in a 3% solution of epsom with metro added and feeding it for 7 to 10 days.
Erythromycin has VERY limited uses. in fact Minimal at best. its best use is in the cases of true symptoms of dropsy or popey (not actual diseases but symptoms of the disease thats normally a gram positive bacteria or an issue with Kidney failures) It should be dosed orally again as it is slow to absorb and that fresh water fish do not drink. But this would be different then a normal bloat.
Most green terror have issues with Hexamita in the gut and the cause of bloat as well asif fed a lower quality diet with to many fillers or not enough of the correct foods it can cause constipation. This causes the bloating and sometimes impaction. Using the metro and epsom while getting on better food is normally the best answer.
kanamycin sulfate is best left for very specific bacterial infections such as Aeromas, Flexorbacter/Flavobacterium, saprolegina and other specific bacterial issues. It is one of the few antibiotics that can be dosed in water or oral as it is a tissue soaking. Its not something thats effective against bloat issues. It does lean more towards gram negative aerobic bacterial issues.