Hi Roz,
Sounds like you've got all the bases covered there.
Garamycin specifically covers eye/ear infections, the Omnipen is a broad-spectrum antibiotic - basically ampicillin (penicillin) - and the bactrim has 2 ingredients to target penicillin-resistant bacteria.....yup, between the lot of them you should get this nailed!
BTW, I give garamycin to my doglet when she gets eye-infections (no comparison intended

) - it always works!
I do hope you get through this very soon and start to feel better,
all the best