Dog - Digestive Issue - Remedy not working

Hi - about 1 month ao my dog vomited a lot of clear gelatenous liquid and stopped eating for 5 days and drank lots and lots of water. I gave him Arsenicum Album 30c every 2 hours and by the second day he was eating and going for walks again. He steadily improved and even had energy levels I havent seen in years--up until yesterday.

This past week he got picky again with eating and I noticed him eating a little grass here and there. Today he woke up has no interest in food and only wants to lay around or go out and eat grass. He had a normal stool earlier today. He tried to vomit a couple of times but nothing coming out. Only drank a very little bit of water, where last time he was drinking insane amounts of water.

I gave him Arsenicum album a few times in the last few hours and Im not seeing results. A month ago it would knock him out within 10-15 minutes and hed wake up refreshed and wanting to eat a little.

Should I try Aresenicum 200ck? I also have on hand Arsenicum 1M, Ignatia amara 30c, Tarentula cubensis 30c, Cantharis 30c, Bach Rescue Remedy, and Bach walnut.

Thank you in advance for any guidance provided here.

Tom