You can give the chewables but the capsules seem better.
They are much cheaper online than from the store.
There are what I get:
Cosequin Regular Strength (90 capsules)
Not sure if this link will work.
I'm not sure who said that Clavamox killed their dog but unless it was an allergic reaction/anaphalaxia (which probably would've happened already if your girl is allergic), then I highly doubt it. It is very similar to a human taking amoxicillan/penicillin. Cosequin is very safe but some stomach upset can occur.