I would put her outside if she's stressed. Let her with the flock if she's not being picked on. If she is, a large kennel setup in the coop/run would help give some protection and she can still be with them.
Yes you can use the Safeguard paste - dosage is the same - 0.23ml per pound of weight given orally 5 days in a row. Just take one of your syringes, stick it in the end of the tube and draw up the correct dose.
(just say "no" to pea size dosing. Everyone's perspective on what a "pea size" actually is differs. Whenever possible use a known "measurement" for dosing. Older threads that you may find do say "pea size" but now we have more current information

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