thin 6-7 week chicks

[lovelychicken]

Hello, my two BA felt pretty thin for a couple weeks but now feel thinner and my other two EE are now feeling very thin as well. You can feel the bone a lot and not much meat on either side of it, the underneath part. Searched to find nothin on thin chickens. They get purina grow and start medicated and very little bits of snacks. They are no longer under heat, lowest it gets here at night is high fifties and low sixties. We do have swarms of mosquitos out but don't think thats it. They seem healthy other wise, they eat/drink and are active. The EE are usually very buff on their weight, meaning heftier. Not sure whats going on, any ideas. I thought maybe they had worms or something. I am new to this, please help.

 

[dlhunicorn]

are they in a brooder setup or are they on the ground?
Where are you located/what is their housing environment and exactly how old are they?

 

[lovelychicken]

they are 6 to 7 weeks old and outside in run during day and coop at night. they felt thin before going outside at night. do they need something extra to feed them to keep their weight on? it says they should be off heat by now. i can add a heater at night to their coop but the mosquitos will go hog wild in their if i do that, they can get through the smallest of cracks.