Back in post #2 I had recommended vitamins and probiotics be given for several days after using Corid for treatment of possible coccidiosis. If you only treated for canker, then you could just give a probiotic.
I'm not an expert on blackhead or trichmoniasis, but I think that cecal worms are what causes it. Valbazen will treat them. Blackhead is fairly rare in chickens, but common in turkeys.
I would get some Corid and treat her for possible coccidiosis. Treat her with 2tsp of the liquid or 1.5 tsp of the powder per gallon for 5-7 days. Afterward give her several days if vitamins and Probiotics. Then I would worm her with Valbazen or Safeguard liquid wormer in case she has worms...