Oh no, poor Ripley.
Clavamox is some nasty stuff. It made Phoenix sick as well. Maybe that is the reason why he is fighting you so much. They only thing I can think off is wrap him very tight in a towel and have your husband hold him down on the kitchen counter. This is easier because it’s eye level. Squeeze his cheeks open with one hand while puling up his face a bit and than use the pill shooter quickly with your other hand. I always give them their favorite treat afterwards. You have to be sneaky opening the pill bottle as well, so he can’t hear you.
I hope and pray that Ripley will get better soon