止める means “to stop”, so in this sentence it would be “was stopped” because it’s in past and passive. So here it’s “I was stopped by the doctor” or “The doctor stopped me”. 病気で means “because of the sickness” and 飲んじゃった is 飲んでしまった. Deepl (which is much better than Google translate 
) translates this as: “I drank alcohol even though I was sick and the doctor had stopped me.”
You can also ask these things here /o/ Short Grammar Questions (Part 1)