HELP! Can you over treat for coccidia??

I am a newbie to raising chickens. History: I have BO chicks now 11 wks old I've had since a few days old. On medicated feed from the start. Lost one chick at 3 wks & went on BYC & consensus was coccidia. First treatment was with Sulmet because it was all I could find at the time. A week after the sulmet treatment, I found Corid & treated with that 1.5 tsp/ gallon water for 7 days. I lost another chick around 5-6 weeks & consensus was to treat with Corid again. Same dose & duration. I had another chick get sick & I did a 3rd round. I have never seen blood in the stool of any of the chicks up until yesterday. I keep trays under the roost. Yesterday I saw 1 stool with mucous & red area like blood. Today there was even more. If I am seeing blood, it can't be good. I don't see roundworms or tapeworms & like I said they are only 11 wks old. I am starting Corid again but maybe I have treated too often??? What else can cause blood in the stool? I also had mites in the coop & treated chicks with permethrin poultry dust & the coop with liquid permethrin & repeated 5 days later. I retreated today because I saw a mite in their poop tray. Also about a weak ago I isolated one on the chicks for what seems respiratory, wet sounding breath sounds & she was listless. There is no visible blood in her stools & she is still away from the others. The well chicks (3) show no signs of respiratory issues are active, eating & drinking, have pink beaks, don't seem anemic. I don't know if the blood in stool is just from one chick or all 3. Most of the poop except 1 -2 droppings look OK. I just recently had a small yard tractor made for them & have let them out in the grassy area the past week or so. There are a lot of weeds, could any weeds cause this? I am adding pictures. Thanks in advance for any advance. Please, even though I know people mean well, I am not ready to cull these chicks yet, I want to give them a chance.

You can overtreat for anything. Too much of a good thing is always a bad thing.]
The bags of medicated feed I've read say not to use anti-coccidial drugs while feeding their product cause they could be overdosed.
If you want to dose with corid. Do so but I wouldn't also feed medicated.
IMHO, people are too quick to tell others to treat for coccidia. Birds in brooders with dry bedding almost never have coccidiosis.
4+ treatments on top of medicated feed should never be necessary.
I've only treated one flock one time with Corid in many years of raising chicks and never use medicated feed.
I think you have something else going on. What were the symptoms when you lost the chicks that made you and others suspect coccidia?
Infectious bursal disease, blackhead, ulcerative enteritis, campylobacteriosis, Newcastle among other things can cause bloody feces.

If it were me, I'd lose all the meds, go back to basics, give some probiotics and some vitamins - especially thiamine. Whatever you do, don't overdo it.

The symptoms of the other chicks were listless, not eating or drinking, the beaks looked pale, no pink to them. These 3 chicks have beaks that are pink especially at the base. I only kept the chicks on the medicated feed because someone on BYC suggested doing so. I am too new at this to know what is the right advise to take. I have older chicken not on medicated feed in a separate coop area that have never acted ill. I can start giving these chicks the unmedicated feed, but I am very worried about the blood. It is bright red so I feel sure it must be blood. I am torn whether I should give the Corid again or not. I'm rather attached to these little girls since I raised them from biddies. The older chicks were 8 - 9 wks old when I got them. Also I checked all chicks vent area & didn't see any blood around that area.