HELP. Not sure what to do with this ivermectin that came in .

From my previous posts I have a rooster whose legs are in pretty bad shape. He is a small guy and people suggested I got ivermectin. says it's for horses. I've been giving his 0.2 ml of antibiotics and safeguard which is a dewormer for about 5 days now and I don't know if I should wait a certain amount of day before introducing him to ivermectin orally since he's been taking a dewormer already. Not sure if im only supposed to give it to him orally or on his legs as well because Reddit suggested he had leg mites and other stuff going on with his legs.