My inclination would be to leave the lesion alone since it is not interfering with her eating. With pigeons, canker can occlude the throat and must be removed. I use a Q tip and gently but forcibly remove it. Yes, she will bleed if you remove the canker. Are you medicating the water for the other chickens? If they drink from the same fount or eat from the same feeder, they may be exposed. If at all stressed or compromised, they too may develop canker. My guess is that your hen is dealing with two problems the initial infection and possible abscess (being controlled by the penicillin) and canker being caused by the Trichomonas taking advantage of her stressed condition. Continue treating as you are. Realize that she may remain as a carrier of Trichomonas even once symptoms disappear.