What would be the best type of medication to buy other then Betta Fix for fin rot?

Don't buy any medications for fin rot - fin rot is caused by dirty water and is cured by keeping the water clean. You don't mention anything about the environment you keep your betta in, but the absolute minimum requirements are a 2.5 gal tank (ideally 10 gal) with a filter that you've cycled, weekly 25 - 30% water changes with aged, treated water. If there is a reason you absolutely must house a betta (temporarily!) in a bowl, use no less than a 1 gal bowl (covered!) and do water changes every few days (weekly at the very least) adding a bit of java moss to the bowl will help, since you won't have any helpful nitrifying bacteria to keep the nitrates/nitrites down.

In my experience the best treatment for fin and tail rot is - a water change and adding aquarium salts and if you feel medications are needed I recomend Mardel's TriSulfa.

Hope this helps and that your beta gets happy and healthy.
Fantails and Betas