Wow, great job!
Amoxicillin - 6.5 / 2.2 x 125 = ~370 mg twice a day (1.5 capsules twice a day), or maybe 1 capsule three times a day.I'm mixing the amoxicillin capsules with a bit of water and giving it to him with a syringe (3 capsules 3 times a day like you said).